Walcutt's thesis is that naturalism in American literature is an offspring of transcendentalism. He sees literary Naturalism as a philosophy that partly defies Nature and partly submits to Nature. The works of naturalist writers of the early twentieth century possess a tension not present in works of the nineteenth century.
Probably the most extensive rendition of the developments of American literary naturalism, its forbearing links in American realism, its movement of and through 19th century scientific positivism, determinism (Darwin) and through into iterations or versions of naturalism in authors like Steinbeck and Hemmingway. However, the book suffers from an explicit formalism that posits something like a perfect form of naturalism which Walcutt sees occuring in Stephen Crane--while all work leading up to and receding after Crane is either evolving or devolving forms of the narrative device naturalism