We take a position on what a work of art is made of. Twelve things: how it feels, how charged it is, its tension, whether it resolves, whether it moves, how big it is, its light, its warmth, how full it is, whether someone is there, whether it sits in a moment, and how close you stand. Four independent readers read the work along those twelve lines. Where they agree, that is the essence. Where they split, that is surface, and the other medium may lose it.

A poet writes a poem that carries the essence, under strict rules of form. A painter who never saw your picture paints the poem alone. The readers read the painting. The distance between the painting's essence and your picture's essence sends the poet back to revise. It stops when the distance stops shrinking.

At the end a second poet, who has seen nothing but the painting, writes the poem back. If that poem shares its essence with the first one, the poem survived its own round trip. That is what we mean when we say every picture has a poem.