Gilbert Highet, The Art of Teaching
(New York: Knopf, 1950), p. 244:
The same arduous type of challenge, without compulsion but with all its difficulty, was given to one of the most distinguished of American educators, Mr. Abraham Flexner. His adviser, Professor Morris of Johns Hopkins, told him that if he wanted to master Greek, he should get a compact little shelf of Greek books and read nothing but Greek for five years. "Read the daily papers to keep up with the world," he said, "but don't read books in any other language. Read Greek only." The ambitious young student took this hard advice, and, like the pupils of Agassiz, he gazed at the intricate subject until he really felt at home in it. Just as they could take a new specimen and see a thousand things which would escape the untrained eye, so he could pick up a book (an immortal book, a permanently valuable book) in Greek, and read it through with ease and pleasure. Such efforts are painful; but without effort there is no reward.