For your teachers, they must be Nature and History: as for the first, that you must learn of it is so obvious that I need not dwell upon that now: hereafter, when I have to speak more of matters of detail, I may have to speak of the manner in which you must learn of Nature. As to the second, I do not think that any man but one of the highest genius, could do anything in these days without much study of ancient art, and even he would be much hindered if he lacked it.