Plato, Ion

[530c] his thought and not merely learning off his words, is a matter for envy; since a man can never be a good rhapsode without understanding what the poet says. For the rhapsode ought to make himself an interpreter of the poet's thought to his audience; and to do this properly without knowing what the poet means is impossible. So one cannot but envy all this.

Ion
What you say is true, Socrates: I at any rate have found this the most laborious part of my art; and I consider I speak about Homer better than anybody, for neither