The Mental Life of the Monkeys 189 



the question an importance commensurate with the part 

 it has played historically in animal psychology. For I 

 think it can be shown, and I hope in a later monograph 

 to show, that reasoning is probably but one secondary 

 result of the general function of having free ideas in great 

 numbers, one product of a type of brain which works in 

 great detail, not in gross associations. The denial of reason- 

 ing need not mean, and does not to my mind, any denial 

 of continuity between animal and human mentality or any 

 denial that the monkeys are mentally nearer relatives to 

 man than are the other mammals. 



So much for supererogatory explanation. Let us now 

 turn to a more definite and fruitful treatment of these 

 records. 



The difference between these records and those of the 

 chicks, cats and dogs given on pages 39-65 passim is un- 

 deniable. Whereas the latter were practically unani- 

 mous, save in the cases of the very easiest performances, 

 in showing a process of gradual learning by a gradual 

 elimination of unsuccessful movements, and a gradual 

 reenforcement of the successful one, these are unanimous, 

 save in the very hardest, in showing a process of sudden 

 acquisition by a rapid, often apparently instantaneous, 

 abandonment of the unsuccessful movements and a selection 

 of the appropriate one which rivals in suddenness the 

 selections made by human beings in similar performances. 

 It is natural to infer that the monkeys who suddenly re- 

 place much general pulling and clawing by a single definite 

 pull at a hook or bar have an idea of the hook or bar and 

 of the movement they make. The rate of their progress 

 is so different from that of the cats and dogs that we cannot 

 help imagining as the cause of it a totally different mental 

 function, namely, free ideas instead of vague sense-impres- 



