i Animal Life and Ours 343 



" But because man's physical structure has been developed 

 from an animal form by natural selection, it does not necessarily 

 follow that his mental nature, even though developed part passu 

 with it, has been developed by the same causes only. " Wallace 

 then goes on to show that man's mathematical, musical, artistic, 

 and other higher faculties could not be developed by variation and 

 natural selection alone. "Therefore some other influence, law, or 

 agency is required to account for them." Indeed this unknown 

 cause or power may-have had a much wider influence, extending 

 to the whole course of his development. "The love of truth, the 

 delight in beauty, the passion for justice, and the thrill of exulta- 

 tion with which we hear of any act of courageous self-sacrifice, are 

 the workings within us of a higher nature which has not been 

 developed by means of the struggle for material existence." At 

 the origin of living things, at the introduction of consciousness, in 

 the development of man's higher faculties, " a change in essential 

 nature (due, probably, to causes of a higher order than those of the 

 material universe) took place." "The progressive manifestations 

 of life in the vegetable, the animal, and man which we may 

 classify as unconscious, conscious, and intellectual life probably 

 depend upon different degrees of spiritual influx." 



In discussing problems such as this there is apt to be misunder- 

 standing, for words are "but feeble light on the depth of the un- 

 spoken," and perhaps no man appreciates his brother's philosophy. 

 Therefore, I refrain from seeking to controvert what Wallace has 

 said, especially as I also believe that the nature of life and mind 

 are secrets to us all, and that the higher life of man cannot be 

 explained by indefinite variations which happened to prosper in the 

 course of natural selection. 



But it seems to me (i) to be difficult to divide man's self into 

 an animal nature which has been naturally evolved and " a 

 spiritual nature which has been superadded," or to separate man's 

 higher life from that of some of the beasts. (2) When we find 

 that any fact in our experience, such as human reason, cannot 

 be explained on the theory of evolution which we have adopted, it 

 does not follow that the reality in question has not been naturally 

 evolved, it only follows that our theory of evolution is imperfect. 

 A theory is not proved to be complete because it explains many 

 facts, but it is proved to be incomplete if it fails to explain any. 

 Thus if man's higher nature cannot be explained by the theory of 

 natural selection in the struggle for existence, then that theory is 

 incomplete, but there may be other theories of evolution which are 

 sufficient. (3) It is difficult to know what is meant by spiritual 

 influx for our opinions in regard to those matters vary with 

 individual experience. We may mean to suggest the interpola- 



