Robert Frost repeatedly warns his readers, sometimes openly, often mischievously, to look for further implications in his poems and not to stop with their obvious associations. In 1927 he said, “I almost think a poem is most valuable for its ulterior meanings . . . I have developed an ulteriority complex.” This view about his writing has been increasingly acknowledged by his more critical readers from the second half of the twentieth century as they explore the deceptively homespun New England persona and subject matter of many of Frost's poems and discover the many subtle ways that they embody and play with the forms and thought of our literary tradition, including the Bible, as well as much of the theological, philosophical, and scientific thought of an increasingly global world. It is clear from his critical writings and from his talks that he wanted the public to recognize this aspect of his work and was annoyed by how slow most of his readers were to grasp it. The question to ask a poet, he said, is “not what he means but what he's up to”(CPPP, 823). His readers failed to see what he was up to, how large a world of forms and ideas he was drawing on.