It is a great thing, indeed, to make a proper use of the poetical forms, as also of compounds and strange words. But the greatest thing by far is to be a master of metaphor. It is the one thing that cannot be learnt from others; and it is also a sign of genius, since a good metaphor implies an intuitive perception of the similarity in dissimilars.
Aristotle, The Rhetoric & The Poetics of Aristotle
metaphor, mot-juste