Darwin now had the basic framework of his theory of natural selection, but he was fully occupied with his career as a geologist and held back from compiling it until his book on "The Structure and Distribution of Coral Reefs" was completed. As he recalled in his autobiography, he had "at last got a theory by which to work", but it was only in June 1842 that he allowed himself "the satisfaction of writing a very brief abstract of my theory in pencil".