Stevens' literary correspondence discloses some of the factors that determine the character of his later poetry. These formative elements are his changing concept of the ideal nature of poetry, his habits of work, his tendency to think inductively. Before 1930 Stevens was an advocate of the doctrine of “pure poetry,” but later became interested in the function of thought in poetry. Answering the questions of his critics, he pondered the significance of images and figures in his poems. His discussion of some of these figures shows an inherent tendency to expand them into universale. The pressure of business limited the amount of time Stevens felt he could devote to a poem. He did not build his poems from verbal elements or textual modification. He created from a preliminary meditation and depended for wording on his genius for improvisation. The meditations out of which his poems emerged could be more or less philosophical, or as slight as the evocation of a sense of place. Whatever thought prompted a poem Stevens wished that poem to be a complete idiomatic expression of it.