Plato said this quote

Many are the noble words in which poets speak concerning the actions of men; but like yourself when speaking about Homer, they do not speak of them by any rules of art: they are simply inspired to utter that to which the Muse impels them, and that only; and when inspired, one of them will make dithyrambs, another hymns of praise, another choral strains, another epic or iambic verses- and he who is good at one is not good any other kind of verse: for not by art does the poet sing, but by power divine.