It was the custom for certain editors of art reviews or books to solicit original graphics from artists to insert in their pages as a bonus for the buyer. Such an “extra” kept the magazine or book afloat and if you were the artist you were glad to help, simply by doing what you did anyway.

     –from Dorothea Tanning: Hail Delirium! A Catalogue Raisonné of the Artist’s Illustrated Books and Prints, 1942-1991, New York: The New York Public Library, 1992, p.100.