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as " Papers for the second edition of part I of the Retrospect,"
a " List of my publications, 1793-1836 " established by Miller
himself.

A bibliography of studies of the idea of progress would be
endless and would include a large part of the work done by
Lovejoy. I shall mention here, almost at random, only a few
titles such as Lois Whitney, Primitivism and the Idea of Progress
in English Popular Literature of the Eighteenth Century (Bal-
timore, 1934) ; Howard Mumford Jones, Ideas in America (Gam-
bridge, 1944) ; Ronald S. Crane, " Anglican Apologetics and the
Idea of Progress, 1699-1745," Modern Philology, Vol. XXXII,
Nos. 3 and 4 (Feb. and May, 1934) ; Rutherford E. Delmage,
" The American Idea of Progress, 1750-1800," Proceedings of the
American Philosophical Society, Vol. 91, No. 4 (October, 1947) ;
Theodor E. Mommsen, " St. Augustine and the Christian Idea of
Progress," Journal of the History of Ideas, Vol. XII, No. 3 (June,
1951) ; Robert E. Palmer, Catholics and Unbelievers in Eight-
eenth Century France (Princeton, 1939) ; Gladys Bryson, Man
and Society: The Scottish Inquiry of the Eighteenth Century
(Princeton, 1948) ; and Adolf Koch, Republic Religion (New
York, 1933) . With the exception of Robert E. Palmer, however,
the authors of these studies do not seem to have emphasized the
distinction between progress and perfectibility— many of them
use either term indifferently or list them together.

122

OWSEI TEMKIN

An Historical Analysis of the Concept of
Infection*

N-i^y.-,^> 1 ,.^.^.^IatJhi.^ l ..^.^>..'^i.^.,^i, ll >i. l ,>>i ll % u

The most recent edition of one of our standard medical dic-
tionaries defines " infection " as follows: " Invasion of the tissues
of the body by pathogenic organisms in such a way that injury
followed by reactive phenomena results." l This definition shows
the earmarks of modern medical research. It is only since about
1800, the days of Bichat, that we have become accustomed to speak
of the tissues of the body. The words " pathogenic organisms "
remind us of the rise of bacteriology. Obviously, a definition of
infection like the above could hardly have been formulated
before the days of Pasteur, Koch, and Lister. And the qualifica-
tion that the presence of pathogenic organisms, though necessary,

* In partly different form and under different title, this article was origi-
nally presented as a paper before the Sigma Xi Society, in Ithaca, N. Y., in
1952. Because of the great role of infection in medicine, the article is, by
necessity, incomplete as to historical details and literature quoted. The
following works may be cited as supplementing some of its omissions: C. E. A.
Winslow, The Conquest of Epidemic Disease, Princeton University Press,
1943; Richard H. Shryock, The Development of Modern Medicine, New York,
Knopf, 1947; John E. Gordon, Evolution of an Epidemiology of Health, in
The Epidemiology of Health, Iago Galdston, editor, New York-Minneapolis,
Health Education Council, 1953; also Vilmos Manninger, Der Entwickelungs-
gang der Antiseptik und Aseptik, Breslau, 1904 (Abhandlungen zur Geschichte
der Medicin, Heft XII) .

1 The American Illustrated Medical Dictionary. Twenty-second edition
Philadelphia, W. B. Saunders Co., 1951, p. 738.

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is not sufficient, that injury followed by reactive phenomena must
have resulted, points to an even more recent date. In short, the
above definition of infection seems to be scientifically accurate,
consisting, as it does, mainly of terms which bear a well defined
connotation verifiable by observation. I say mainly, because here,
as elsewhere in medicine, there remains an element of more
doubtful character. What exactly is an " injury," and what is
an " invasion " ? We shall come back to these disturbing elements
in the definition. For the moment let us be content with the fact
that the modern concept of infection is reasonably clear and
that it is couched in the language of modern science.

This being the case, we may be all the more permitted to
wonder at the incongruity between the definition and the term
defined. The word " infection," as well as its counterparts in
other languages, is much older than the nineteenth century.
I need hardly point out that infection is derived from the Latin
infectio. Now, one may easily say that there is nothing unusual
in an old term receiving a more precise explanation with the
advance of science. People talked about " fever " long before
they knew how to measure the temperature of the body, and of
" pneumonia " before any post mortem dissections had been
performed on human bodies. Infection must have occurred at
all times; the word expresses a phenomenon that has remained
the same, although its scientific explanation was reserved for a
more advanced age. Encouraged by this thought, we turn to
ancient medical literature and we find indeed that Theodorus
Priscianus, a physician of the fifth century a. d., devotes a whole
chapter to " infectio " in his textbook of medicine. However,
the chapter is entitled: De infectionibus capillorum, 2 i. e., " On
the dyeing of hair." We shall have to admit, I think, that the

"■Theodorus Priscianus Euporiston libri III, ed. Valentine Rose, Lipsiae,
1894, I, c. 2, p. 5 if.

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An Historical Analysis of the Concept of Infection

matter is not quite as simple as we assumed. The word included
a connotation which it no longer possesses today.

There is no other way but to inquire more closely into the
meaning of those words which have come to be used for the
concept of infection. The Latin " infectio," as we just heard,
means staining or dyeing. And to stain or to color is one of the
principal connotations of the verb " inficere." The root meaning
of this word is to put or dip into something, and the something
may be a dye; or to mix with something, especially a poison;
or to stain something in the sense that it becomes tainted, spoiled,
or corrupted. Indeed, the English word " to stain " can still be
used in the double sense of dyeing as well as polluting. Let us
remember, then, that an infection is basically a pollution. And
the same is true of the term " contagion " which indicates a
pollution, especially by direct contact. Peculiarly enough, the
Greek verb miaino presents a counterpart to the Latin inficere.
Here too the mere staining can be included together with physical
or moral defiling. And the corresponding noun " miasma " origi-
nally meant any pollution or polluting agent.

This brief linguistic excursion will suffice to bring out a basic
element in the concept of infection: impurity. If we look for
examples we have only to turn to chapter 13 of Leviticus which
deals with Zara'ath, the disease commonly translated as leprosy.
"And the leper in whom the plague is, his clothes shall be rent,
and his head bare, and he shall put a covering upon his upper
lip, and shall cry, Unclean, unclean. All the days wherein the
plague shall be in him he shall be defiled; he is unclean; he shall
dwell alone; without the camp shall his habitation be" (ch. 13,
vs. 45 and 46) . The leper is obviously isolated so that he may
not communicate his uncleanness; for persons, animals, and
things unclean make those who come in contact with them
unclean too. This, according to the Bible, holds true of men

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suffering from gonorrhea, and of men and women in the sphere
of sexual functions; it holds true of the beasts that are unclean
and forbidden food; and it also holds true of dead objects.

The chapter dealing with Zara'ath greatly influenced the
medieval attitude towards leprosy and the segregation of lepers.
The contagiousness of leprosy was dreaded beyond the real
danger of infection. Nevertheless, this attitude may have helped
to make those countries where regulations were rigorously
enforced almost free of leprosy around 1600. No wonder that
the sanitary significance of Leviticus has been greatly praised,
especially since washing of clothes and bathing in water were
mandatory in the process of purification! 3 It is not necessary
to deny that, as far as leprosy, gonorrhea, and the eating of
carrion flesh are concerned, an empirical insight into the real
danger existed. But the guiding thought was that of a ritualistic
religious taboo. " Thus shall ye separate the children of Israel
from their uncleanness; that they die not in their uncleanness,
when they defile my tabernacle that is among them." 4 The dis-
eases mentioned as unclean in Leviticus are but one type of
pollution among others. 5 We are not even quite certain exactly
what disease Zara'ath was. Even if it included what we now
call leprosy, 6 it must have included other conditions as well. The
sufferer from Zara'ath might recover and be cleansed from his
impurity. On the other hand, even garments and houses could
be affected by Zara'ath.

According to an age-old belief, disease could be sent by the
gods as punishment for a crime with which men had defiled

3 Leviticus, ch. 14, v. 8.

4 Leviticus, ch. 15, v. 31.

5 Wolf von Siebenthal, Krankheit als Folge der Stinde, Hannover, 1950,
passim, has shown a similar relationship in other civilizations between disease
and pollution.

This has been doubted by F. C. Lendrum, /. A.M. A., 1952, vol. 148, p. 222.

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An . Historical Analysis of the Concept of Infection

themselves. The Bible mentions leprosy as well as plague as
instances. According to the Greeks, Apollo shot his plague arrows
upon the Greek host before Troy because their leader, Agamem-
non, had abducted the daughter of his priest. The girl had to be
returned. "And," as Homer tells us, " they purified themselves,
and cast the defilement into the sea, and offered to Apollo
acceptable hecatombs of bulls and goats by the shore of the
unresting sea." 7 Likewise, Apollo sent the plague upon Thebes
because Oedipus, the King, had killed his father and married
his mother, so that a pollution, a miasma, infested the land. 8
The ideas of a disease caused by a foul deed, and of a disease
defiling the sufferer, were almost interchangeable.

Around 400 b. c, a Greek physician wrote a book " On the
Sacred Disease," the popular name for epilepsy, in which he
attacked the popular healers. " For the sufferers from the disease
they purify with blood and such like, as though they were
polluted, bloodguilty, bewitched by men, or had committed some
unholy act." But to the belief that gods or demons might cause
the disease, our author opposes his own enlightened view: " How-
ever, I hold that a man's body is not defiled by a god, the one
being utterly corrupt the other perfectly holy. Nay, even should
it have been defiled or in any way injured through some different
agency, a god is more likely to purify and sanctify it than he is
to cause defilement." 9 This opposition of a natural explanation
of disease to the religious or magic one which is expressed in the
so-called Hippocratic writings is of great import for the concept

'Homer, Iliad, I, 314-316. Translation by A. T. Murray, Loeb Classical
Library, I, p. 27. E. R. Dodds, The Greeks and the Irrational, Berkeley,
1951, p. 36, claims that the belief in pollution as infectious was post-Homeric;
see, however, my review in Isis, 1952, vol. 43, p. 375 f.

8 Sophocles, Oedipus the King, 96-98.

9 Hippocrates, with an English translation by H. W. S. Jones, Loeb Classical
Library, II, p. 149.

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of infection. Speculating on the significance of air, another
Hippocratic author reasons that pestilences or epidemic fevers
must be due to the air that all men inhale at the same time.
"So whenever the air has been tainted with such pollutions
(miasmasin) as are hostile to the human race, then men fall
sick . . . ." 10 Keeping within the old terminology of miasma,
a secularization has been achieved. The plague is no longer con-
sidered a punishment for religious or moral defilement; instead
it has become the result of a defilement of the air, due to some
mysterious agents suspended in it. The transmutation is not
even so startling as we might think at first. In the myths it is
the sun god Apollo that sends pestilences, now it is still the
sky— especially the sun— that acts upon the air. " Why is it that
when considerable vapor arises under the action of the sun, the
year is inclined to plague? " asks a somewhat later philosopher. 11
We have it on good ancient authority that the forecasting of
" droughts and rainstorms and plagues and earthquakes and
other changes in the surrounding vault of a similar character "
was considered a serious part of astronomy not on a par with
the casting of nativities. 12

Medicine from Antiquity to the Renaissance is replete with
references to planets and conjunctions that breed pestilences and
new diseases. The name for " influenza " is derived from the
influence of the stars. But there is also intermingled a good deal
of climatology that may be wrong but not dependent upon ideas

10 Ibid., p. 235. I have substituted " tainted " where Jones has " infected."

11 Pseudo-Aristotle, Problems, I, 21. Translation by W. S. Hett, Loeb
Classical Library, I, p. 19. According to a late Greek source (Clemens Alex-
andrinus) the Egyptians too derived epidemics from the sun; see Theodor
Puschmann, Die Geschichte der Lehre von der Ansteckung, Wien, 1895, p. 4.

12 Sextus Empiricus, Against the Professors, V, 2. Translation by R. G. Bury,
Loeb Classical Library, IV, p. 323. On Aristotle's theory, e. g. to explain
evaporations and earthquakes by action of the sun, cf. Otto Gilbert, Die
meteorologischen Theorien des griechischen Altertums, Leipzig, 1907, p. 307.

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An Historical Analysis of the Concept of Infection

of universal sympathy and astral spirits. At any rate the notion
that epidemic diseases were connected with weather and winds,
seasons, floods, and earthquakes remained firmly established until
the second half of the nineteenth century. Here again it is hard
to say where actual experience of the seasonal prevalence of such
diseases as infantile paralysis, malarial fevers, upper respiratory
infections, diarrhea of infants, and others ended and where
meteorological speculation, which saw in epidemics, a telluric
event of divine or cosmic origin, began.

II

Although all diseases could conceivably be judged as punish-
ment for crime, it appears that there existed a popular classi-
fication of diseases into clean and unclean, the latter being
" infections " par excellence. Of these latter, we mentioned
leprosy, gonorrhea, plague, and epilepsy, to which insanity
might be added. In the popular mind these types of diseases
had and have a moral or religious stigma. The plague as God's
wrath at a sinful people, leprosy and venereal disease as filthy,
mental disease as a disgrace, are notions very much alive even
today. In former times these diseases were popularly considered
not only as pollutions but also as possibly catching. The super-
stitious Greek or Roman spit when he met insane or epileptic
persons, and people were afraid to eat or drink from a dish an
epileptic had used. The pressure of opinion seems to have
induced medieval physicians to uphold this belief, at the same
time rationalizing it by a natural explanation. The breath of
the epileptic was now accused of carrying the contagion. This
explanation was ready-made since the ancients had ascribed
such a role to the breath in other diseases, e. g., consumption.

129

Ml

MH

jjgBgajjffi

Studies in Intellectual History

Only in the sixteenth century was the fable of the contagiousness
of epilepsy definitely eliminated from the medical literature. 13
Although the occurrence of contagion among men and animals
was known to the ancients, they did not elaborate the concept
systematically." It is still one of the great puzzles of historical
pathology that such infections as measles, scarlet fever, and
smallpox are not recorded in classical literature. Did they not
exist, or were they not conceived as specific diseases? Whatever
the answer may be, the fact remains that the first systematic
enumeration of contagious diseases is to be found in the so-called
Book of Treasure, an Arabic textbook of medicine, compiled
not later than about 900 a. d. The author enumerates the fol-
lowing contagious diseases: " Leprosy, scabies, small-pox, measles,
ozaena, ophthalmia and the pestilential diseases." 15 To this list
we may add a Latin one, dating from the thirteenth century,
naming acute fever, consumption, epilepsy, scabies, ignis sacer,
anthrax, ophthalmia, and leprosy. 16 These lists show a con-
siderable knowledge of " contagious diseases, that is those which
infect others," as they were called," although their nosological
interpretation is not easy. Karl Sudhoff explained the "acute
fever" as plague or typhus, and "ignis sacer" as erysipelas,

13 See O. Temkin, The Falling Sickness, Baltimore, The Johns Hopkins Press,
1945, pp. 7 and 114ff.

"See Puschmann, Die Geschichte der Lehre von der Ansteckung, Wien,
1895; Karl Sudhoff, Infektionsverhiitung im Wandel der Zeiten und An-
schauungen. Reprinted in Arch. Gesch. Med., 1929, vol. 21, pp. 207-218. The
concept of medical infection is clearly expressed in Thucydides' account of
the plague, especially II, 51 where he uses the same verb " anapimplemi "
that also carries the notion of "defiling."

15 Max Meyerhof, The " Book of Treasure," an Early Arabic Treatise on
Medicine, Isis, vol. 14, 1930, pp. 53-76, see p. 61.

10 Karl Sudhoff, Die acht ansteckenden Krankheiten einer angeblichen
Baseler Ratsverordnung vom Jahre 1400. Reprinted in Arch. Gesch. Med.,
vol. 21, 1929, pp. 219-227, see p. 224 f.

"Ibid., p. 227: " Hit sunt morbi contagiosi, id est inficientes alios. . . ."

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An Historical Analysis of the Concept of Infection

although ergotism is just as likely an interpretation. Sudhoff
was obviously guided by the idea that these diseases should be
infectious from our point of view. The naming of ozaena in
the Arabic list, together with epilepsy in the Latin one, shows
how misleading this may be. Ozaena is a condition characterized
by a foul discharge from the nose. Quite possibly it was the
evil smell that led to the belief of contagiousness. Nevertheless,
we may say that the clinical study of infectious diseases was well
under way. By the middle of the sixteenth century, the nervous
diseases had been eliminated from serious medical consideration,
while syphilis, typhus, scarlet fever, and influenza had been
added. The further development of this clinical knowledge is
outside our theme. Instead we have to return to the theory of
infection as pollution and the associations it evoked of some-
thing bad, to be avoided and if possible removed.

Ill

The statement that epidemic disease is caused by miasms, i. e.,
pollution of the air, in itself seems to have given the illusion
of an explanation. This illusion was supported by the meaning
of infection as staining. The analogy with a tincture where a
small drop of dye-stuff suffices to color a large amount of fluid
played an important role in medieval alchemy and medicine.
It helped to explain how the whole body could become sick
from mere contact or inhaled breath. 18 Finally, and perhaps most
important, there was the decay and putrescence of organic bodies,
" sepsis," to cite the Greek word which we still use. Putrescence
became the pattern of pollution and the evil smell it propagated

18 Aretaeus, VIII, 131, speaking of the communicability of elephantiasis
(leprosy) refers at once to the " baphe " (in the sense of the Latin " infectio ")
and its transmission (" metadosis ") by the breath.

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was taken as an indication and guide. To quote an old English
version of a medieval poem, the so-called School of Salerno:

Though all ill savours do not breed infection,
Yet sure infection commeth most by smelling 19

The evil smell from the refuse of slaughter houses and from
a sick person was supposed to cause infection, as was the unplea-
sant odor hovering over marshes, the malaria, bad air, of later
days. The latter in particular was called "virus," a word that
could also designate the poisonous secretion of snakes. A chain
of associated words and images thus provided a theory of infec-
tion, and it is remarkable how our modern terminology has
remained within the orbit of ancient and medieval imagery.
Indeed, the fight against epidemic diseases was guided by very
similar notions in the fourteenth century and in the middle of
the nineteenth. In 1347 bubonic plague, the black death, began
its devastating reign and stimulated the creation of public health
measures in medieval towns in times of pestilence. The streets
were cleaned, the keeping of pigs and the emptying of cesspools
were forbidden. In England the first general statute against
nuisances was enacted in 1388. 20 To cleanse the air, pyres were
lighted in the streets, the rooms and beds were scented with
vinegar and perfumes. Since evil smell caused sickness, a pleasant
one would remove it. 21 Here we witness the fallacy of ascribing
physical effects to what was pleasant, a confusion of science and
aesthetics. Pyres disappeared in the eighteenth century when

18 The School of Salernum, New York, Hoeber, 1920, p. 87.

20 John Simon, English Sanitary Institutions, London, 1890, p. 41, note.

21 The idea of fire and good odors combating the plague goes back to
antiquity. Galen, Ad Pisonem de theriaca liber, c. 16 (ed. Kiihn, vol. 14,
p. 281) tells the story of Hippocrates who ordered the Athenians to have
fires lighted throughout their city and to use the best smelling substances as
fuel.

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An Historical Analysis of the Concept of Infection

better means of ventilation were invented, but in many respects
the great sanitary movement of the nineteenth century followed
in the old medieval footsteps. It started in England in the 1830's
under the impact of the asiatic cholera that had invaded Europe
in 1831 and of the appalling morbidity and death rate of the
working population herded into the cities by the industrial
revolution. These people lived in squalor and filth, and the
sanitarians directed their efforts against these conditions. This
is what John Simon, one of the medical protagonists of public
health, in 1874, had to say of the fatal influence of uncleanliness:

... I do not refer to it in its minor degrees, as compared
with high standards of cleanliness or chemical purity, but
refer chiefly to such degrees of it as fall, or ought to fall,
within the designation of FiLTH:-to degrees, namely, which
in most cases obviously, and in other cases under but slight
mask, are such as any average man or woman should be
disgusted at: such as, eminently, the presence of putrescent
refuse-matter, solid and fluid, causing nuisance by its efflu-
via and soakage. Also in imputing to Filth, as thus illus-
trated, that its effluvia are largely productive of disease, I do
not ignore that disease is also abundantly caused by air
which is fouled in other ways. 22

More briefly and poetically the same thought had been
expressed in the following verses:

In houses where you mind to make your dwelling,

That neere the same there be no evill sents

Of puddle-waters, or of excrements,

Let aire be cleere and light, and free from faults,

That come of secret passages and vaults. 23

Today we distinguish between disinfectant and deodorant.

22 John Simon, Public Health Reports, vol. 2, London, 1887, p. 450.

23 The School of Salernum, op. cit.,. p. 87.

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Studies in Intellectual History

But as long as pollution of the air was a guiding concept,
including any impurity noticeable to the senses or by its alleged
results, such a distinction was almost impossible to make. In
1881, Littre's dictionary still defines " disinfection " as: "Action
d'enlever a 1'air, a un appartement, aux vetements, aux divers
tissus organiques, ou a un corps quelconque, les miasmes dan-
gereux ou les odeurs desagreables qui les infectent." 2i It is,
therefore, not astonishing to see that physicians and surgeons in
using disinfectants or antiseptics largely relied on their deodorant
effect. Thus Semmelweis, who in 1847 discovered that childbed
fever was caused by " disintegrating organic material " carried
by the attending obstetricians, prescribed disinfection of hands
with chlorinated lime, guided by the deodorant action of this
substance. 25

As regards the scientific explanations of infection originating
between the late Middle Ages and about 1850, they did not con-
tribute much to a better understanding either, ingenious and
interesting, nay even prophetic, as many isolated contributions
were.

Limiting ourselves to a very brief survey, we find Fracastoro,
in the sixteenth century, elaborating a theory of contagion that
summarizes ancient and medieval experience; while Syden-
ham in the seventeenth century reformulates epidemiological
doctrines. 26 According to Fracastoro, contagious diseases spread

34 E. Littre, Dictionnaire de la Langue Francaise, T. 2, Paris, 1881, p. 1105.

26 Ignaz Philipp Semmelweis, Die Aetiologie, der Begriff und die Prophylaxis
des Kindbettfiebers, in Gesammelte Werke, ed. Tiberius von Gyory, Jena,
G. Fischer, 1905, p. 130: " Dass nach der gewohnlichen Art des Waschens der
Hande mit Seife die an der Hand klebenden Cadavertheile nicht sammtlich
entfernt werden, beweist der cadaverose Geruch, welchen die Hand fur
langere oder kiirzere Zeit behalt."

20 For details cf. C. E. A. Winslow, op. cit.

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An Historical Analysis of the Concept of Infection

by a transfer of imperceptible particles (seminaria) 37 from an
infected body to another by direct contact, via an intermediate
object (fomes) , or at a distance. 28 While infection can originate
in a sick body spontaneously, contagion accounts for the trans-
mittal of the same disease to other bodies. Infection, primary
as well as induced, is a form of putrescence. 29 The most original
feature in Fracastoro's work, apart from his clinical differentia-
tion of typhus and other diseases, is his insistence that the seeds
of contagion are particles which can even propagate themselves in
neighboring parts, and his differentiation of two kinds of putre-
faction, one accompanied by " a stench and a disgusting taste " 30
and the other which may proceed without it like the change of
wine into vinegar. These views are interesting regardless of
whether Fracastoro really anticipated the fermentative, or enzy-
matic, action involved in infectious processes or merely realized
that there were different ways for things to get spoiled.

Sydenham's interest, conforming with his intention to imitate
Hippocrates and to describe diseases as they appeared and dis-
appeared, centered on the epidemic constitution of years and
seasons. It is not too great an exaggeration to say that the medical
theory of infection around 1850 had not progressed considerably
beyond these two men. For one thing it was very much confused.
Infection was used synonymously with, or differently from, con-
tagion. If distinguished, infection was attributed to agents
consisting " almost entirely of decayed or diseased organized

27 Hieronymus Fracastorius, De contagione et contagiosis morbis et eorum
curatione, libri III. Translation and notes by C. Wright, New York, Putnam,
1930, book I, ch. 3, p. 10.

28 Ibid., ch. 2 ffi.

29 Ibid., especially chs. 1, 3, and 9.

30 Ibid., ch. 9, p. 41. Although Fracastoro hardly believed in the organismic
nature of these particles, such a view became widespread towards the end of
the seventeenth century, see Manninger, op. cit., p. 26 ff.

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substances, and of animal emanations or secretions . . . found to
exist most abundantly in marshy and alluvial soils, in slaughter-
houses, common-sewers, dissecting-rooms, graveyards, and in those
places where a large number of living persons are crowded to-
gether, particularly if the effluvia of their excretions taint the
atmosphere. Such places are called centres or foci of infection,
because from the morbid influence there concentrated, disease
spreads in every direction." 31 The infectious agents or miasms
were usually supposed to enter the system through the lungs.
Contagious diseases " strictly so called " were those " which can-
not be traced to any other source than communication mediate
or immediate with persons already attacked by them, and which
cannot be referred to any atmospheric or other external cause,
or combination of causes, but only to pre-existent causes of the
same kind . . . ." 32

The existing confusion can best be documented by another
quotation from the same author, Stille of Philadelphia.

A cargo of rags from the Levant arrives at one of our
ports, and on being discharged, creates disease in all the
neighbourhood of the vessel; if the disease thus originating
is like one which was prevalent at the place whence the
cargo came, the rags are a source of contagion. If there is
no such similarity, or there was no prevalent disease at the
Eastern port, then the newly-arisen malady must be attri-
buted to the filth of the cargo, which is, in that case, a
source of infection. 33

No wonder that there was violent disagreement over the infec-
tious or contagious character of such diseases as plague, cholera,
and yellow fever! 34 This controversy was embittered by the

An Historical Analysis of the Concept of Infection

practical consequences that if these diseases were contagious,
ships from suspected countries had to be quarantined for a
lengthy period of time. The confusion was further heightened
by the assumption of "septic poisons, or those which are gen-
erated by putrefaction," and were believed to enter the body
with the food, through the air, or " through a wound as so
frequently happens to those engaged in anatomical studies." 35
But whether infection or contagion, the question remained how
the virus acted in the body from the moment of its introduction
to the outbreak of the disease. Stille cites Liebig as believing
in a fermentative action comparable to that of yeast. " Other
observers," he adds, " upon the ground of an alleged discovery,
that leaven acts by propagating vegetable germs, suppose the
different sorts of virus to contain animal ova, or vegetable germs,
which, by rapid generation, fill the body with parasitic insects
or invisible plants, whose presence constitutes the disease."
Stille recommends waiting till the microscope has " revealed the
existence of either of these sorts of bodies." 36

We have cited Stille's work at some length as a representative
example of generally accepted medical theory. The book
appeared in 1848 when the great sanitary movement was under
way in England and when demands for public health reform
were heard on the Continent as well. If it is true that the
insight into the nature of infectious disease had not changed
much between 1550 and 1850, then the intensification of the
fight against infection must be due to other factors which had
relatively little to do with an understanding of its mechanism.

31 Alfred Stille, Elements of General Pathology, Philadelphia, 1848, p. 95.
™Ibid., p. 100. * 3 Ibid., p. 101.

s * See Erwin H. Ackerknecht, Anticontagionism between 1821 and 1867,
Bull. Hist. Med., 1948, vol. 22, pp. 562-593.

136

30 Still<§, op. cit., p. 93.
3 «Ibid., p. 104f.

137

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IV

Viewed in long-range perspective, the intensification of the
fight against " filth " that animated the sanitarians can be seen
as a stage in the process of civilization, a consequence of the ever
increasing interdependence of men since the Middle Ages. 37 It
can also be seen as specifically conditioned by industrialization,
urbanization, and outbreaks of cholera, 38 and facilitated by the
use of statistical methods. In addition, however, it can be under-
stood as a changing attitude towards cleanliness.

Looking backwards we have difficulties in gauging the degree
of cleanliness of past ages as judged by modern standards. 39
We are too easily misled by superficial analogies with our customs
and their allegedly rational motives. For instance, the medieval
custom of frequenting a bathhouse has been hailed as an impor-
tant chapter in the history of hygiene. Undoubtedly persons
bathing regularly will acquire a certain degree of cleanliness,
although bathing is, of little avail if the clothes are not kept
clean too. 40 There are even medieval pictures showing groups
of people using a tub and otherwise cleaning themselves. But
other pictures, showing men and women bathing together, eating,
drinking, and listening to music, indicate that the main attrac-
tion was not cleanliness but pleasure or the medicinal effect of
water. 41

37 Norbert Elias, Tiber den Prozess der Zivilisation, 2 vols., Basel, Haus zum
Falken, 1939.

as See above, p. 133.

30 Material bearing on this and related questions will be found in Cabanes,
Mosurs intimes du passe, Paris, Albert Michel; Norbert Elias, op. cit., and
Reginald Reynolds, Cleanliness and Godliness, New York, Doubleday and
Company, 1946.

40 This has been emphasized by J. F. D. Shrewsbury, The Plague of Athens,
Bull. Hist. Med., 1950, vol. 24, p. 11.

41 The medicinal effect of bathing has to be clearly separated from its
hygienic one. According to Meuli, Scythica, Hermes, 1935, vol. 70, pp. 121-

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An Historical Analysis of the Concept of Infection

As late as 1752, a passage in Smollett's Essay on the External
Use of Water, one of the few medical writings of the novelist,
expresses the traditional evaluation. " Indeed," he writes, " the
warm Bath is so well understood in its Anodyne capacity, that
every body (almost) after the fatigue of a journey, or other
hard exercise, has recourse to the Bagnio for refreshment: and so
agreeable is the operation of this medicine, that in ancient times,
as well as in these days, it has been considered as a point of
luxury and pleasure . . . ." 42

At the same time, the religious and ceremonial meaning of
purity or cleanliness still stands very much in the foreground.
Thus the large German encyclopedia published by Zedler around
1750 contains detailed discussions of the meaning of purity in
the Bible, while the same entries have nothing to say about
worldly cleanliness. A book by the famous Dr. Friedrich Hoff-
mann, that appeared in 1722 and described how to enjoy health
and long life in conformity with the teachings of Holy Writ, is a
popular text on personal hygiene. 43 It mentions food, drink, the
use of wine, baths, and tobacco— with hardly a word about
cleanliness.

All this goes to show that as late as the eighteenth century
the avoidance or removal of substances because of their poten-

176, there is also a relationship between the Finnish bath and shamanism.
For pictorial material see Alfred Martin, Deutsches Badewesen in vergangenen
Tagen, Jena, Diederichs, 1906.

42 Tobias Smollett, An Essay on the External Use of Water, edited with
introduction and notes by Claude E. Jones, Baltimore, The Johns Hopkins
Press, 1935, p. 61 (italics mine) . Praise and blame of bathing can be found
in Martial's epigrams and is succinctly expressed in the School of Salernum,
loc. cit., p. 84:

" Wine, women, Baths, by Art or Nature warme,
Us'd or abus'd do men much good or harme."

43 jjerrn Friederich Hoffmanns Gruendlicher Unterricht etc., Ulm, Daniel
Bartholomai, 1722.

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tially harmful physiological action has not yet become the leading
concept in the idea of cleanliness. This " physiological concept "
of cleanliness is however gaining ground, especially, it would
appear, in the Anglo-Saxon countries, concomitant with sanitary
reforms in the army, navy, and jails.

It has been stated that cleanliness used to be a matter of
aesthetics. 44 The truth of this is confirmed by Francis Bacon's
dictum: " For cleanness, and the civil beauty of the Body was
ever esteemed to proceed from a modesty of behaviour, and a
due reverence in the first place towards God, whose creatures we
are, then towards society, wherein we live; and then our selves,
whom we ought no less, nay, much more to revere, than we do
any others." 45 These lines occur under " Cosmetic " which,
according to Bacon, relates to the beauty of the body rather
than to its health. Shortly afterwards, the theme is taken up by
George Herbert who demands of the country parson that " his
apparrell [be] plaine, but reverend and clean, without spots, or
dust, or smell; the purity of his mind breaking out and dilating
it selfe even to his body, cloaths, and habitation." ie Elsewhere
Herbert generalizes this sentiment in the following verses:

Affect in things about thee cleanlinesse ,

That all may gladly board thee, as a flowre.

Slovens take up their stock of noisomnesse
Beforehand, and anticipate their last houre.

44 Henry E. Sigerist, Civilization and Disease, Cornell University Press, 1943,
p. 26.

46 Francis Bacon, Of the Advancement and Proficiencie of Learning, Inter-
preted by Gilbert Wats, London, 1674, Book 4, ch. 2, p. 130.

46 The Country Parson, ch. 3, in: The English Works of George Herbert, ed.
G. H. Palmer, 3 vols., Boston and New York, Houghton Mifflin and Company,
1905; vol. 1, p. 214. The parson is also to teach that " alter religion . . .
three things make a compleate servant: Truth, and Diligence, and Neatnesse
or Cleanlinesse " (ibid., p. 237) .

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An Historical Analysis of the Concept of Infection

Let thy minde's sweetnesse have his operation
Upon thy body, clothes, and habitation."

The last two lines are used by John Wesley in 1791 in his
sermon " On Dress," in which he argues that " slovenliness is no
part of religion " and that Scripture nowhere " condemns neat-
ness of apparel. Certainly this is a duty, not a sin. ' Cleanliness
is, indeed, next to godliness.' Agreeably to this, good Mr.
Herbert advises every one that fears God:-

Let thy mind's sweetness have its operation
Upon thy person, clothes, and habitation.

And surely every one should attend to this, if he would not
have the good that is in him evil spoken of." 48

It has been noticed long ago that Wesley refers to " Cleanliness
is next to godliness " as to a proverb. 49 However that may be,
the significance of the quotation does not lie in the expression
of a new truth; rather it lies in the religious fervor with which
" the lower and middle ranks of life," i. e., those whom scripture
forbids " to be adorned with gold, or pearls, or costly apparel," 50
are admonished to keep themselves clean in appearance. Wesley
wanted the dress of the Methodist to be plain as well as cheap.
This meant that he could not easily hide dirt under perfumes
and fashionable clothes. To the Methodist—as probably to the
Quaker and others before him— cleanliness becomes a sign of
respectability, and that means that even the respectable poor
are now expected to avoid dirt.

Significantly enough, the stress on the religious meaning of

" The Church Porch, LXII, ibid., vol. 2, p. 57.

48 John Wesley, " Sermon 88, On Dress " in Works, vol. 7, fifth edition,
London, 1860, p. 16. For the date, 1791, see N.E.D. s.v. "Cleanliness."

49 W. Davenport Adams, Dictionary of English Literature, new and revised
edition, London, Paris and New York, Cassell Potter and Galpin, p. 138.

50 John Wesley, loc. cit., p. 17.

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cleanliness is paralleled by increasing emphasis upon its medical
meaning. As a preacher, John Wesley quoted Herbert; as a lay
medical adviser he quoted the physician George Gheyne. The
latter, in his Essay of Health and Long Life, had said: " Every
one, in order to preserve their Health, ought to observe all the
Cleanness and Sweetness in their Houses, Cloaths, and Furniture,
suitable to their Condition." 51 With slight changes, these lines
reappear in the preface to John Wesley's Primitive Physic, dated
1747. 52

There are other voices, apart from Wesley's, praising the
medical and moral virtues of cleanliness. Dr. William Buchan,
in his famous Domestic Medicine, a popular medical handbook,
has a chapter " Of Cleanliness " in which it is recommended " as
necessary for supporting the honour and dignity of human
nature, as agreeable and useful to society, and as highly con-
ducive to the preservation of health." 53 Reversing the order,

51 George Cheyne, An Essay of Health and Long Life, London, 1724, p. 18.
The particular meaning of these words evinces from p. 12: " Nor shall I add
any pressing instances, to avoid wet Rooms, damp Beds, and foul Linnen,
or to remove Ordure and Nusances; the Luxury of England having run all
these rather into a Vice."

62 John Wesley, Primitive Physic: or, An Essay and Natural Method of
Curing most Diseases. Twenty-first edition, London, 1785, p. xiii: " Every one
that would preserve health, should be as clean and sweet as possible in their
houses, clothes and furniture." The date of the preface is given on p. xvi.
The role of John Wesley in the spread of a " health " movement has probably
been over-emphasized by Sir George Newman, Health and Social Evolution,
London, Allen and Unwin; 1931, p. 61; cf. Shryock, op. cit., p. 90. Moreover,
Sir MacFarlane Burnet, in the Lancet of Jan. 17, 1953, p. 103, has drawn
attention to the efforts made in the nineteenth century to impart the relatively
high standards of cleanliness of upper class society to its lower strata. But
it seems nevertheless important to note the currents among other than
aristocratic and well-to-do circles.

53 William Buchan, Domestic Medicine: or, A Treatise on the Prevention
and Cure of Diseases by Regimen and Simple Medicines. Second edition,
London, 1772, p. 131. The whole chapter (VIII) is worth attention because
of the inferences it allows to the widespread prejudice against cleanliness in
the case of sick people.

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«MMMaH^MMMIMIIAHnaHIMIH[

An Historical Analysis of the Concept of Infection

John Pringle, the British army physician, says: " Cleanliness is
conducive to health, but is it not obvious, that it also tends to
good order and other virtues? " 5i And Benjamin Rush, who
quotes these lines with approval, states that " too much cannot
be said in favour of cleanliness, as a physical means of pro-
moting virtue." E5

The insistence on cleanliness is vague as long as it is not
accompanied by definite requirements. In 1794, Dr. Hufeland,
in his treatise on long life, suggested not only daily washing but
even, if possible, a daily change of linen. 56 For the majority of
the population, the latter was as yet a Utopian demand. How-
ever, the introduction of the Leblanc process, in 1791, for the
manufacture of soda, and the contemporary revolution in the
cotton industry laid the preconditions for an eventual realiza-
tion of this Utopia. At any event, by the end of the eighteenth
century, the physiological concept of cleanliness had not only
been greatly advanced over previous times but had also become
imbued with a moral and religious force. Cleanliness was trans-

" Quoted from Benjamin Rush, An Inquiry into the Influence of Physical
Causes upon the Moral Faculty (1786) , Philadelphia, 1839, p. 15. Rush refers
to Pringle's " oration upon Captain Cook's Voyage, delivered before the Royal
Society in London " as his source (ibid.) . In his Observations on the Diseases
of the Army, seventh edition, London, 1775, p. 92. Pringle writes that " officers
judge rightly with respect to the health of the men, as well as to their
appearance, when they require cleanness both in their persons and clothes."
Remarkably enough, he believes that "plague, pestilential fevers, putrid
scurvies, and dysenteries, have abated in Europe within this last century;
a blessing which we can attribute to no other second cause, than to our
improvement in every thing relating to cleanliness, and to the more general
use of antiseptics " (p. 332) . Regarding London, he admits that there is room
for hygienic improvement, but adds that " some of the main points have been
well attended to; such as regard the privies, the common sewers, and the
supplies of fresh water; and the people in general are very cleanly " (p. 335) .

56 Rush, loc. cit.

56 Christopher William Hufeland, The Art of Prolonging Life. Translated
from the German, 2 vols., London, 1797; see vol. 2, p. 236.

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Studies in Intellectual History

ferred from the domain of cosmetics to that of health, and with
the Enlightenment, the appeal to health became an ever more
powerful motive for action. Guided by their own rationalization
of life, men also rationalized the past. The laws of the Bible
imposing the ritualistic stamp of clean and unclean were now
explained as wise sanitary prescriptions by a shrewd law giver."
This change in the mentality of modern man also brought about
a change in his concept of infection.

V
The nineteenth century completed what we may call the secu-
larization of the concept of infection by redirecting the basic
meaning of the term, by giving it a new scientific content and
a new moral force. If we look up the words " infection " and
" to infect " in the New English Dictionary, we find that the
medical meaning is emerging as the most concrete one. The
notion of immersing or staining an object has become obsolete
and so has the notion of impurity in the chemical sense of an
alloy or the adulteration of a substance. The medical meaning,
in various shades, stands in the foreground and overshadows the
other broader meanings of corruption and defilement. The latter
still exist but seem relegated to the status of similes and meta-
phors. Such a semantic circle was made possible by the purge
to which the Enlightenment of the eighteenth century had
subjected everything "superstitious." But the semantic change
could not have been achieved without filling the notion of
infection with a more strictly scientific content than it had had
before. This was done by the rising science of bacteriology
which substituted pathogenic microorganisms for the miasmata,
contagia, effluvia, and corruptions of old. It would be repetitious

67 See e. g. Rush, loc. cit.

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An Historical Analysis of the Concept of Infection

to recount the well-known tales of Schwann who proved that
putrefaction needed an external agent; of his colleague Henle,
at the Berlin laboratory of Miiller, who postulated the identity of
contagions and miasms, believing in the organic nature of both;
of Josiah Nott's animalcular theory of the transmission of yellow
fever; and of John Snow's theory of cholera propounded a few
years later. The endeavors of these and many others prepared
the way for Pasteur's investigations and the work of Robert Koch
and Joseph Lister. Much resistance had to be overcome, yet by
1900 the victory was complete. To dwell upon the progress
which has since been made would be to repeat another often
told tale. Instead we had better sum up what we have said so far.
We started out with the observation that our modern medical
concept of infection emerged from the notion of ritualistic or
religious pollution of which disease was but one type. The Greek
physicians accepted this older terminology, at the same time
giving it a naturalistic turn. This was the first secularization of
the concept. I must leave it to those better trained psychologi-
cally to decide how successful this turn was. I expect that they
will claim that a good deal of the dread of higher powers and
of feelings of guilt still are hidden in our minds. During the
Middle Ages and Renaissance we found a progressive recognition
of what, today, we call infectious diseases. The belief in disease
entities of a specific character was strengthened in the nineteenth
century by the discovery of bacteria as specific etiologic agents.
The interpretation of infection as resulting from filth guided
public health measures in the medieval cities as well as in the
industrial centers of the early nineteenth century. The notion
proved insufficient and was replaced by deepened scientific
insight. But the emergence of nineteenth century hygiene and
bacteriology and asepsis were themselves conditioned upon will-
ingness to rationalize the conduct of life in accordance with

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An Historical Analysis of the Concept of Infection

medical rules. This process, initiated in the eighteenth century
by a widening regard for individual cleanliness, led to the second
secularization of the concept of infection. The medical meaning
of the word, backed throughout by the sciences of bacteriology
and immunology, has become the prime meaning.

These are the structural elements of the concept of infection
which our historical analysis has revealed to us. To check its
completeness we turn once more to the definition from which
we started. Infection, we read, is an " invasion of the tissues of
the body by pathogenic organisms . . . ." We may stop here
and wonder again about the use of the curious word " invasion,"
reminiscent of hostile armies whose onslaught ought to be
resisted. If we had looked up another dictionary we might have
found another word instead of " invasion." Yet some image
seems necessary to explain the encounter between the human
being and his enemies, the pathogenic organisms.

In its early enthusiasm of some seventy years ago, the bacteri-
ological school believed that man plus germ equalled disease.
It was then realized that the matter was not so simple and that
natural or acquired immunity and somatic as well as psychic
disposition had to be taken into account in order to explain
why some people fall ill, while others remain healthy; and
why the same person may long harbor germs before the
germs suddenly produce disease. It was during that period that
Dr. Ottmar Rosenbach, in an essay still worth reading, pointed
out the similarity between the old protective measures against
evil spirits defiling man's soul and the extreme bacteriologist's
endeavor to protect the welfare of the body. 58 Far from accepting
Dr. Rosenbach's analysis as criticism, I believe that he really
laid bare a necessary desideratum. As long as infection was held

68 O. Rosenbach, Physician versus Bacteriologist, New York and London,
1904, p. 247.

to be a pollution, it was understandable in human terms. It was
punishment for a trespass, a sin, or a crime, or merely the
danger threatening from a supernatural power. At any rate,
man thought he knew why he had become infected.

The nineteenth century tried to break radically with this
anthropomorphic heritage. It succeeded as far as the explanation
of the mechanism of infection is concerned. The bacteriologist's
job was to find out what happened after man and germ had
met. Why had they met? As far as the bacteriologist was con-
cerned, this question was irrelevant. " By accident," he might
say, if an answer was insisted upon. But as a physician, or
public health officer, or citizen, the same bacteriologist took
quite a different attitude. The more he came to know about
the mechanics of infection, the more he believed that he knew
how infection could and should be avoided. Responsibility for
the prevention and cure of infection has now become a moral
and even political force which it never was before. This being the
case, our attitude has to be acknowledged as part of our concept
of infection. In defining infection as an injury caused by an
invasion by pathogenic microorganisms, we indicate our readiness
to resist them. Modern physics boastfully or plaintively speaks
of the meaningless universe. But there is no meaningless uni-
verse in medicine. Human beings are not satisfied with viewing
health and disease as matters of mere chance separable from their
lives. Health, diseases, recovery, and other medical categories
mark biological conditions as desirable or undesirable. The latter
characteristic accounts for the medical nature of the concept of
infection and for its persistence under different cultural con-
ditions with different notions about the fight against pollution.

147