36 THE PATH OF SCIENCE 



ability of the child or of the primitive Negro to reproduce 

 line and form is low. In the same way, the ability of artists 

 to dra^v or of sculptors to design and carve or of architects 

 to design and build has varied at different periods. Their 

 technical skill is not constant. The artist who drew the stele 

 of Bellicia may have drawn it in that form because he thought 

 it was beautiful, but it is absurd to imagine that that artist 

 was the equal in technical skill of the artist who carved the 

 Attic tombstones of the fifth and fourth centuries B.C. It is 

 very easy in a country like Eg)pt, where the standards of 

 judgments did not vary, to observe the variation in the tech- 

 nical ability of the painters, sculptors, and architects. The 

 carvings in the tombs show mastery over the subject, w^hich 

 increased as the cycle progressed, and then the style became 

 limited and stiff and conventional as decadence set in. This 

 is not a change in objective; the objects represented are the 

 same. It is a change in skill, in the mastery of the art. In 

 the decadent stage it is not uncommon to find that the artists 

 copied the designs of an earlier period because they recog- 

 nized that they had not the ability to originate designs of the 

 same quality as those which they were copying. 



If, then, we accept Petrie's view of the existence of these 

 cultural cycles, let us follow his discussion of their origin. 

 After considering the effects of changes of climate, which 

 have often produced migrations of peoples, Petrie considers 

 that the rise of a new civilization is conditioned by the im- 

 migration of a different people; that is to say, it arises from 

 a mixture of two different stocks. The effective mixture can- 

 not take place all at once. When a new stock migrates into 

 a country, usually in a military invasion, there is an appre- 

 ciable barrier between the two races. But such barriers 

 always give way in time ^vhen the t^vo races are in contact, 

 and in seven or eight centuries the two races are completely 

 blended. Petrie concludes, therefore, that the cycle is started 

 by the invasion of a new stock, which introduces an archaic 

 period superimposed on the decadent style of the previous 

 cycle, and then, as the new stock blends with the old, artistic 



