272 COMTE TO BENJAMIN KIDD CHAP. 



past our planet is said to have passed through more 

 than one ice age. Of course so tremendous a change in 

 environmental conditions involved the forfeiting of past 

 progress. The tests were all (however gradually) 

 altered. The last became first, and the first last. The 

 unfit were now found fit, while the fit proved unfit. 

 Physiological capital was fatally depreciated, like 

 machinery thrown out of use by a better invention. 

 Only here there was no better invention. There was no 

 continuous progress. There was discontinuity and a 

 change of conditions. Evolution then will scarcely 

 mean progress unless Jirst it is continuous evolution. 

 But continuity in evolution of species implies constancy 

 of environment. No doubt, speaking broadly, we have 

 had such continuity on the earth for a good many 

 aeons. 



Secondly, a difficulty occurs as to those species 

 which seem unchanged from remote geological times. 

 Drummond's Ascent of Man has been the one of our 

 authorities which has told us most about these. There 

 are shells, it seems, absolutely unchanged through 

 many ages, because they had "arrived." They had 

 reached the limit of possible development on the line 

 which they had chosen. More important still is the 

 case of man, whose physiological improvement, accord- 

 ing to Fiske, has been superseded and arrested by the 

 emergence of reason, and whose cranial development, 

 according to Professor Cleland, has gone about as far 

 as is possible under the laws of space in their bearing 

 on the constitution of the human body. We cannot 

 therefore say in spite of all Darwinising moralists 

 that " everything is in flux," moving " from change to 

 change eternally." Evolution seems to be a definitely 

 limited movement, exhausting its possibilities, now in 



