Instinct and E durability 443 



and that this method of study offered a wide and rich field for 

 investigation. Of course those who regarded the study of mind only 

 as a branch of metaphysics smiled at the philosophical ineptitude of 

 the mere man of science. But the investigation, on natural history 

 lines, has been prosecuted with a large measure of success. Much 

 indeed still remains to be done ; for special training is required, and 

 the workers are still few. Promise for the future is however afforded 

 by the fact that investigation is prosecuted on experimental lines 

 and that something like organised methods of research are taking 

 form. There is now but little reliance on casual observations recorded 

 by those who have not undergone the necessary discipline in these 

 methods. There is also some change of emphasis in formulating 

 conclusions. Now that the general evolutionary thesis is fully and 

 freely accepted by those who carry on such researches, more stress is 

 laid on the differentiation of the stages of evolutionary advance than 

 on the fact of their underlying community of nature. The conceptual 

 intelligence which is especially characteristic of the higher mental 

 procedure of man is more firmly distinguished from the perceptual 

 intelligence which he shares with the lower animals — distinguished 

 now as a higher product of evolution, no longer as differing in origin 

 or different in kind. Some progress has been made, on the one hand 

 in rendering an account of intelligent profiting by experience under 

 the guidance of pleasure and pain in the perceptual field, on lines 

 predetermined by instinctive differentiation for biological ends, and 

 on the other hand in elucidating the method of conceptual thought 

 employed, for example, by the investigator himself in interpreting 

 the perceptual experience of the lower animals. 



Thus there is a growing tendency to realise more fully that there 

 are two orders of educability — first an educability of the perceptual 

 intelligence based on the biological foundation of instinct, and 

 secondly an educability of the conceptual intelligence which re- 

 fashions and rearranges the data afforded by previous inheritance 

 and acquisition. It is in relation to this second and higher order of 

 educability that the cerebrum of man shows so large an increase of 

 mass and a yet larger increase of effective surface through its rich 

 convolutions. It is through educability of this order that the human 

 child is brought intellectually and affectively into touch with the 

 ideal constructions by means of which man has endeavoured, with 

 more or less success, to reach an interpretation of nature, and to 

 guide the course of the further evolution of his race — ideal con- 

 structions which form part of man's environment. 



It formed no part of Darwin's purpose to consider, save in broad 

 outline, the methods, or to discuss in any fulness of detail the results 

 of the process by which a differentiation of the mental faculties of 



