Some quotes about poetry (and art) from The Christian Imagination (which happens to be a fantastic book of essays on the "practice of faith in literature and writing"). These are quotes in the book, not quotes from the book.
The poet's job is not to tell you what happened, but what happens: not what did take place but the kind of thing that always does take place. --Northrop Frye, The Educated Imagination
The poet is not a man who asks me to look at him; he is a man who says "look at that" and points. --C.S. Lewis, The Personal Heresy
It is the function of all art to give us some perception of an order in life, by imposing an order upon it. --T.S. Eliot, On Poetry and Poets
You use a glass mirror to see your face; you use works of art to see your soul. --George Bernard Shaw, Back to Methuselah
A poem is the very image of life expressed in its eternal truth. --Percy B. Shelley, A Defense of Poetry
Reading poetry gives experiences there is no other way to have. It gives them quickly, suddenly, just about whenever we want. --Kenneth Koch, Making Your Own Days: The Pleasures of Reading and Writing Poetry
Poetry provides the one permissible way of saying one thing and meaning another.... We like to talk in parables and in hints and in indirections. --Robert Frost, "Education in Poetry"