THE LOGICAL STATUS OF MENTAL FACTORS 113

factor being specified by a particular pattern of bodily
measurements.

(i) The general factor responsible for the majority of the resem-
blances will obviously describe the general physical shape character-
istic of all human beings as such—the ideal form or Gestalt that
distinguishes man from all other creatures. This first factor there-
fore defines, in terms of physical measurements,1 the persons'
essential humanity : in short, it states the genus to which the whole
sample belongs.

(ii) In certain sub-groups, however, we shall find marked and
typical deviations from this generic shape. Half the individuals,
for example, will have broader hips, narrower shoulders, and tinier
extremities than we should otherwise expect ; the remaining half
will show the reverse peculiarities. This twofold subdivision can
readily be expressed by two subsidiary factors, dividing the entire
sample into two sub-groups or species. Since the first species is the
negative of the second, we can, if we prefer, reduce these two anti-
thetical * group-factors' to a single c bipolar factor.' The group-
factors we may regard as specifying the female species and the male
species respectively : the bipolar factor we may regard as indicating
a differentia, i.e. as differentiating the females from the non-females.
No doubt, if we continued, we should encounter other group- or
bipolar factors differentiating old from young, broad-headed races
from narrow-headed races, Kretschmer's ' pyknic' type from the
c leptosomic,' and so on.

(lii) Since no individual is a perfect specimen of the species or type
to which he belongs, but always varies slightly from its ideal or
average shape, and that in a way which is unique, we shall ultimately
reach a third kind of factor, one for every person, and each character-

1 It will perhaps be the artist's view of humanity rather than the anato-
mist's, Sir Joshua Reynolds's ' central form from which ever/ deviation is
deformity' rather than Quetelet's homme moyen. For centuries, writers on
anatomy for artists have endeavoured to deduce ideal proportions of the
human figure for the benefit of the art-student, and have often appended
a note saying how certain types (the different sexes, the young and the
old) differ from the generalized ideal: in so doing, they have, as it were,
carried out a rough factor-analysis of the type described in the text. The
anatomist usually gives simple and unweighted averages; but for his famous
4 canonical statuette' Carus seems to have based his proportions not on
simple averages of ordinary persons, but rather on weighted averages (as we
should call them), i.e. he gives more value to the measurements of a limb as
found in persons in whom that limb shows a relatively perfect development
(Symbolik des Menschlicben Gestalts, 1857).

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