112 EVOLUTION AND MAN S PLACE IN NATURE 



manifestation of intelligence, simpler or more complex, 1 

 as we trace successive stages of organic advance. The 

 distinction between life physical and life rational first 

 appears to us in the life of the child after birth. In 

 attributing intelligence to the child, we recognise that 

 development by nutrition does not include develop 

 ment of mind. As food and education are reckoned 

 apart, and provided for under different charges, so, 

 when manhood is reached, athletic exercise does 

 not develop mind, though we admire good physique 

 the more when associated with a highly-trained 

 intellect. 



When, on these grounds, it is maintained that 

 mental phenomena cannot be traced to germ-plasm, 

 a new problem is raised as to the appearance of mind 

 in the history of the individual life. Beyond this 

 arises the question whether laws of heredity apply 

 here, as in the physical life. These are problems of 

 great perplexity, first for biological science, as they 

 elude the research of comparative embryology, and 

 next for mental science, as they carry inquiry beyond 

 consciousness, and also beyond outward observation. 

 The presence of mind is certain; the mode of its 

 appearance in the individual history is unknown. The 

 fact is sure, its occurrence must be left to stand as a 

 thing undiscovered. The field of our observation is 

 thus restricted to the relations of the intellectual life to 

 parentage, while we seek evidence for heredity in 

 mind, as in body. All reasoning here must be from 

 the facts of human experience, towards probabilities 

 connected with the origin of intelligent life, and with 

 its subjection to laws of heredity. In default of direct 



1 What the facts are will be considered in next chapter. 



