596 THE POPULAR SCIENCE MONTHLY. 



results : out of a list of thirty-one, seven certainly wrote memoirs or 

 other works under twenty ; fifteen gave out their first known produc- 

 tion between twenty and twenty-five ; three began to write between 

 twenty-five and thirty ; leaving six who, so far as I can judge, entered 

 on the productive stage after thirty. 



If, again, we ask at what age fame, or the achievement which en- 

 titles to fame, is reached, we obtain the following figures : Out of a 

 group of thirty-seven, fourteen reached this point before twenty-five, 

 twelve between twenty -five and thirty ; eight between thirty and forty ; 

 while three did not rise to the height of renown till after forty. 



In science, as in the more serious department of letters, fame is 

 sometimes reached suddenly by the production of a great work, the 

 fruit of many years of study. Harvey's publication of his great dis- 

 covery at the age of fifty is a case in point. It is to be remembered, 

 however, that Harvey had expounded his theory in lectures some 

 twelve years before this date. And the same kind of remark applies 

 to Darwin and others who first gave to the world epoch-making 

 truths at a somewhat advanced age ; we commonly find that the 

 actual discovery dates from a much earlier period, the promulgation 

 of it being deferred till it w r as ready to be presented in a definite and 

 verified form. The case of Franklin making his first, and this a capi- 

 tal, scientific discovery toward the age of fifty is, so far as I can gather? 

 exceedingly rare, if not, strictly speaking, unique. 



Philosophers. If philosophy precedes science in the historical 

 development of the race, we need not wonder at meeting with in- 

 stances of youthful speculative genius. Coleridge is not the only 

 case of a lad of fifteen having his head seething with metaphysical 

 puzzles. But Coleridge, it may be said, never developed into an 

 original thinker ; and what we require is proof of the early manifesta- 

 tion of genuine philosophic originality. 



Passing by the romantic story of Abelard dazzling Paris and Eu- 

 rope with his dialectics at the age of twenty, and coming to the 

 modern period, we note that the most conspicuous instances of philo- 

 sophical precocity are supplied by the history of British philosophy. 

 Berkeley, as his commonplace-book shows, hit on his new principle of 

 idealism at college when only eighteen, an instance of metaphysical 

 audacity to which there is no parallel. His " New Theory of Vision," 

 perhaps the most epoch-making w T ork in the history of psychology, 

 appeared when the author was twenty-four. His immediate successor, 

 Hume, displayed speculative ability when very young, and was re- 

 garded by his mother as an " uncommon wake-minded " lad. His 

 " Treatise of Human Nature," probably the work of modern times 

 which has proved most stimulating to further inquiry, was thought 

 out between the ages of twenty-three and twenty-six. And, oddly 

 enough, Hume's most distinguished follower, J. S. Mill, has supplied 

 the best recent example of philosophic precocity. 



