Who is Chagall from A Coney Island of the Mind, Poems and what is their importance?

Chagall appears in Chapter One: A Coney Island of the Mind, in which, he paints 'The Horse with Violin in Mouth' against his mother's wishes, jumps on the horse and rides away, waving the violin, only to give it away, with a low bow, to the first naked nude he finds with no strings attached.