THE SCIENCE OF HAPPINESS 



thirty. Augustus Caesar ruled half the known world 

 at twenty-two, and all of it a bare ten years later. 

 Napoleon at thirty had behind him a record of almost 

 unexampled conquests, and was supreme arbiter of the 

 destinies of France, if not indeed of all Continental 

 Europe. 



Such men as these, obviously, are not to be judged 

 by their mere years. But, indeed, as just suggested, the 

 year is scarcely an accurate standard of measurement for 

 the life of even the ordinary man. "A man that is 

 young in years," says Bacon, "may be old in hours." 

 Here, then, we have a more rational unit ; but unfortu- 

 nately one that could not well be applied in practice. 

 We cannot well analyse the hours of our fellows, to deter- 

 mine what number of them have been well employed. 

 For practical purposes, the clumsy standard of years 

 must suffice. Perhaps on the whole it serves well 

 enough. 



Just where the threshold of senility should lie, in the 

 course of any individual life, it is impossible to pre- 

 dict with precision, so much depends upon complica- 

 tions of heredity and the minor complications of en- 

 vironment. Somewhere along in the forties, let us say, 

 a man is likely to begin to realise, not without a shock 

 of surprise and an impulse of rebellion, that he is no 

 longer young. He is not yet old, surely; is scarcely 

 at middle age ; but he is not young. His hair has be- 

 gun to change color a trifle ; his figure tends to enlarge 

 a little about the waist-line not the place for muscular 

 development; and he half suspects that he has not quite 



