On the Sublime and Beautiful/Part V/Chapter 6

HENCE we may observe that poetry, taken in its most general sense, cannot with strict propriety be called an art of imitation. It is indeed an imitation so far as it describes the manners and passions of men which their words can express; where animi motus effert interprete lingua. There it is strictly imitation; and all merely dramatic poetry is of this sort. But descriptive poetry operates chiefly by substitution; by the means of sounds, which by custom have the effect of realities. Nothing is an imitation further than as it resembles some other thing; and words undoubtedly have no sort of resemblance to the ideas, for which they stand.