110 MENTAL EVOLUTION IN ANIMALS. 



sations, and if this is the case it becomes evident with what 

 plastic material natural selection has had to deal in moulding 

 through numberless generations the form of consciousness 

 which best fits, with reference to the welfare of the organism, 

 the. circumstances of stimulation. 



Thus we may well believe that survival of the fittest, 

 acting always in co-operation with these principles of psycho- 

 physiology, must have been successful in accomplishing the 

 adjustments here assigned to its agency — the adjustments, 

 that is, between states of consciousness as agreeable or dis- 

 agreeable and circumstances of stimulation as beneficial or 

 deleterious. And thus it is that in the process of evolution 

 organisms "have gone on establishing a consensus between 

 the various organs of the body, so that at last, for the most 

 part, whatever will prove deleterious to any organ proves 

 deleterious also to the first nerves of the organism which it 

 affects," and therefore disagreeable to consciousness, although 

 of course, as we should from these principles expect, this is 

 only the case "when the deleterious object is found suffi- 

 ciently often in the environment to give an additional point 

 of advantage to any species which is so adapted as to 

 discriminate and reject it."* 



Thus then, it seems to me, we have as full a rationaU of 

 Pleasures and Pains as we can expect or need desire. The 

 only difficulty is to understand the connection between the 

 objective fact of injuriousness or the reverse, and the corre- 

 sponding subjective state of consciousness ; how is it that 

 injuriousness or the reverse comes to be, as it were, translated 

 into the language of Pleasure and Pain. But this is only the 

 old difficulty of understanding the connection of Mind with 

 Body, and has no reference to historical psychology, which 

 takes the fact of this connection as granted. Possibly, how- 

 ever — and as a mere matter of speculation, the possibility is 

 worth stating — in whatever way the inconceivable connection 

 between Body and Mind came to be established, the primary 

 cause of its establishment, or of the dawn of subjectivity, 



* Grant Allen, loc. cit., p. 27. The latter consideration disarms any criti- 

 cism which might be advanced against our doctrine on account of the agree- 

 able taste of certain poisons, both to ourselves and to the lower animals. But 

 it is astonishing even here how rapidly the appropriate distaste arises after 

 experience of the injurious effects : witness the dislike of wine which may fre- 

 quently be caused, even in those who are addicted to excess, by surreptitiously 

 mixing it with nux-vomica. 



