It sounds like a simple thing, to say what you see, Mark Doty begins. But try to find words for the shades of a mottled sassafras leaf, or the reflectivity of a bay on an August morning, or the very beginnings of desire stirring in the gaze of someone looking right into your eyes . . . Doty finds refuge in the sensory experience found in poems by Blake, Whitman, Bishop, and others. The Art of Description is an invaluable book by one of America's...