Art collectors and patrons often rely on the advice of such critics as a way to enhance their appreciation of the art they are viewing. Many now famous and celebrated artists were not recognized by the art critics of their time, often because their art was in a style not yet understood or favored. Conversely, some critics, have become particularly important helping to explain and promote new art movements — Roger Fry with the Post-Impressionist movement, Lawrence Alloway with Pop Art as examples.