34 .Heredity and Environment 



p. 125). Consequently it is not possible to hold that bodies gen- 

 erate bodies or even germ cells, nor that souls generate souls. 

 The only possible scientific position is that the mind (or soul) 

 as well as the body develops from the germ. 



Certainty of Mental Development. No fact in human exper- 

 ience is more certain than that the mind develops by gradual and 

 natural processes from a simple condition which can scarcely be 

 called mind at all; no fact in human experience is fraught with 

 greater practical and philosophical significance than this, and yet 

 no fact is more generally disregarded. We know that the greatest 

 men of the race were once babies, embryos, germ cells, and that 

 the greatest minds in human history were once the minds of 

 babies, embryos and germ cells, and yet this stupendous fact has 

 had but little influence on our beliefs as to the nature of man and 

 of mind. We rarely think of Plato and Aristotle, of Shakes- 

 peare and Newton, of Pasteur and Darwin, except in their full 

 epiphany, and yet we know that when each of these was a child 

 he "thought as a child and spake as a child," and when he was a 

 germ cell he behaved as a germ cell. 



Wonders of this Development. The development of the mind 

 from the activities of the germ cells is certainly most wonderful 

 and mysterious, but probably no more so than the development of 

 the complicated body of the adult animal from the structures of 

 the germ. Both belong to the same order of phenomena and 

 there is no more reason for supposing that the mind is supernatur- 

 ally created than that the body is. Indeed, we know that the mind 

 is formed by a process of development, and the stages of this de- 

 velopment are fairly well known. There is nowhere in the en- 

 tire course of mental development a sudden appearance of psychi- 

 cal processes, but rather a gradual development of these from 

 simpler and simpler beginnings. No detailed study has been made 

 of the reactions of human germ cells and embryos, but there is 

 every reason to believe that these reactions are simpler in the 

 embryo and germ cell than in the infant, and that they are gen- 



