Good books, like well-built houses, must have tradition behind them. The Homers and Shakespeares and Goethes spring from rich soil left by dead centuries; they are like native trees that grow so well nowhere else. The little writers--hacks who sentimentalize to the latest order, and display their plot novelties like bargains on an advertising page--are just as traditional. The only difference is that their tradition goes back to books instead of life. Middle-sized authors--the very good and the probably enduring--are successful largely because they have gripped a tradition and followed it through to contemporary life. This is what Thackeray did in "Vanity Fair," Howells in "The Rise of Silas Lapham," and Mrs. Wharton in "The House of Mirth." But the back- to-nature books--both the sound ones and those shameless exposures of the private emotions of ground hogs and turtles that call themselves nature books--are the most traditional of all. For they plunge directly into what might be called the adventures of the American sub-consciousness. It is the sub-consciousness that carries tradition into literature. That curious reservoir where forgotten experiences lie waiting in every man's mind, as vivid as on the day of first impression, is the chief concern of psychologists nowadays. But it has never yet had due recognition from literary criticism. If the sub-consciousness is well stocked, a man writes truly, his imagination is vibrant with human experience, he sets his own humble observation against a background of all he has learned and known and forgotten of civilization. If it is under-populated, if he has done little, felt little, known little of the traditional experiences of the intellect, he writes thinly. He can report what he sees, but it is hard for him to create. It was Chaucer's rich sub-consciousness that turned his simple little story of Chauntecleer into a comment upon humanity. Other men had told that story--and made it scarcely more than trivial. It is the promptings of forgotten memories in the sub-consciousness that give to a simple statement the force of old, unhappy things, that keep thoughts true to experience, and test fancy by life. The sub- consciousness is the governor of the waking brain. Tradition-- which is just man's memory of man--flows through it like an underground river from which rise the springs of every-day thinking. If there is anything remarkable about a book, look to the sub-consciousness of the writer and study the racial tradition that it bears.