VARIABILITY OF RATE OF CULTURAL CHANGE 351

about between its termination and the rise of the XVIIIth ? The answer
can only be a decided negative.'1

This answer might be correct; yet it would not avail, by reason of that,
to prove the case which is here based upon it. It might be true that,
during the interval between the end of the Twelfth Dynasty and the
beginning of the Eighteenth Dynasty, the Egyptiac culture had changed
more than it had changed while the Twelfth Dynasty had been on the
throne; but it would not follow that the time taken by the greater of
these two unequal quanta of change must have been proportionately
longer than the time taken by the lesser quantum. So far from its being
requisite to assume that the rate of change must have been constant, it
would be surprising if the pace of change had in truth been the same in
two periods which were so different from one another hi their social
circumstances. The second of the two was an anarchic interregnum in
which we should expect the pace of change to accelerate, whereas the
preceding period was a time of relative peace, order, and stability in which
we should expect the pace of change to be sluggish. An expectation
based on this difference in character between two periods .would thus
have anticipated the astronomical evidence indicating that the greater
quantum of change during the second period took no longer a time to
come to pass than the smaller quantum during the first period; and, in
fact, by the time when the present chapter of this Study was being
written in A.D. 1950, the consensus of Egyptologists had declared itself
unmistakably in favour of accepting the chronological evidence of
Astronomy without regard for an unconvincing hypothetical law to the
effect that the tempo of psycho-social change is not subject to variation.

This judgement of common sense is strikingly vindicated by indis-
putable facts in a number of cases in which the spans of time taken by
cultural changes comparable in character to the change from a Twelfth-
Dynasty culture to an Eighteenth-Dynasty culture in Egyptiac history
are known to us from chronological records that cannot be impugned by
any subjective estimate of the time required for allowing these cultural
changes to take place.

For example, we know for a fact that the remains of the Temple of
Zeus at Olympia and of the Parthenon at Athens which are still standing
in our day date from the fifth century B.C. ; that the remains of Hadrian's
Olympieum at Athens and of the Temple of the Sun at Ba*lbak date
from the second century of the Christian Era; and that the Church of the
Ayfa Sophfa at Constantinople dates from the sixth century of the
Christian Era. Supposing, however, that we had no record of any of
these dates, and that in the absence of direct evidence we tried to recon-
struct the chronology by making an estimate of the Time-intervals
between the dates of the three sets of buildings on the basis of Hall's
assumption that the tempo of cultural change is invariable, we should be
bound to guess that the Time-interval between the Olympieum and the
Ayfa Sophfa—representing, as these two buildings do, two orders of
architecture that are, not merely diverse, but antithetical in their styles,

* Hall, H. R.: 'Egyptian Chronology1, in The Cambridge Ancient History, voL i> and
ed, (Cambridge 1924, University Press),'pp. 168-9.