362 THE HISTORY OF CREATION. 



of human ancestors sketched in a late chapter gives an ap- 

 proximate representation. 



It is true that this conception generally greatly offends 

 most persons on their first becoming acquainted with the 

 Theory of Development^ because more than all others it 

 most strongly contradicts the traditional and mythological 

 ideas, and the prejudices which have been held sacred for 

 thousands of years. But like aU other functions of organ- 

 isms; the human soul must necessarily have historically 

 developed, and the comparative or empirical study of 

 animal psychology clearly shows that this development 

 can only be conceived of as a gradual evolution from the 

 soul of vertebrate animals, as a gradual differentiation and 

 perfecting which, in the course of many thousands of 

 years, has led to the glorious triumph of the human mind 

 over its lower animal ancestral stages. Here, as everywhere, 

 the only way to arrive at a knowledge of natural truth is to 

 compare kiudred phenomena, and investigate their develop- 

 ment. Hence we must above all, as we did in the examina- 

 tion of the bodily development, compare the highest animal 

 phenomena on the one hand with the lowest animal phe- 

 nomena, and on the other with the lowest human phe- 

 nomena. The final result of this comparison is this — that 

 between the most highly developed animal souls, and the 

 lowest developed humnn souls, there exists only a small 

 quantitative, hut no qualitative difference, and that this 

 difference is much less than the difference between the 

 lowest and the highest human souls, or than the difference 

 between the highest and the lowest animal souls. 



In order to be convinced of this important result, it is 

 above aU things necessary to study and compare the mental 



