[Footnote 1: Epist. I. II.]
But if a man finds himself in possession of great mental faculties, such as alone should venture on the solution of the hardest of all problems--those which concern nature as a whole and humanity in its widest range, he will do well to extend his view equally in all directions, without ever straying too far amid the intricacies of various by-paths, or invading regions little known; in other words, without occupying himself with special branches of knowledge, to say nothing of their petty details. There is no necessity for him to seek out subjects difficult of access, in order to escape a crowd of rivals; the common objects of life will give him material for new theories at once serious and true; and the service he renders will be appreciated by all those--and they form a great part of mankind--who know the facts of which he treats. What a vast distinction there is between students of physics, chemistry, anatomy, mineralogy, zoology, philology, history, and the men who deal with the great facts of human life, the poet and the philosopher!