446 JAMES CLERK MAXWELL. [CHAP. XIV. 



and transmitted from generation to generation, though 

 varying slightly from individual to individual. 



According to the simplest form of the Evolution theory, 

 those individuals, tribes, or species, which have habits un- 

 favourable to their success in the battle of life, die out, and 

 help to improve the average quality of the remainder. This 

 good old rule, however, this simple plan, though it might 

 suffice for beings of great fecundity, would involve a great 

 waste of life among higher and less prolific forms. Hence 

 if any of these should come to have tastes and feelings, and 

 if these should happen to be such as to repel them from per- 

 nicious courses and attract them into salutary ones, this 

 would give them an advantage in the struggle for existence. 

 Of course, there would be an equal chance that the tastes 

 and feelings, when first developed, would be in favour of 

 courses leading to destruction ; but the individuals possessed 

 by these tastes and feelings would be all the quicker exter- 

 minated for the good that is to say, the more vigorous 

 continuation of the species. 



The susceptibility to pleasure and pain must therefore 

 be regarded as permitting a certain mitigation of the first 

 covenant of the evolutionists, " This do and live ; " the 

 original severity of which was all the greater since the word 

 " this " could be interpreted only by observing what actions 

 were not followed by death. 



By pursuing what we feel to be pleasant, and avoiding 

 what we feel to be painful, we are following a course which 

 was probably followed by many of our ancestors, and of 

 which we know at least this much that it did not bring 

 them to such speedy destruction as to prevent them from leav- 

 ing us as their descendants ; and this is more than we can say 

 for any absolutely new rule of life struck out by ourselves. 



But it must be confessed that the monitions of pleasure 

 and pain are not held in such high esteem by all men, as the 

 view which we have just taken would seem to warrant. 

 For though here and there we may find an isolated teacher 

 who has inculcated the cultivation of all forms of pleasurable 

 sensation, and the elimination of whatever is disagreeable, 



