An autobiographic instinct may be as old as Man Writing; but only since 1800 has Western Man placed a premium on autobiography. A bibliography of all autobiographic writing prior to that time would be a small fascicule; a bibliography since 1800 a thick tome. The ground behind this simpleminded assertion of a quantitative measure cannot be explained away by easy reference to the mass literacy of the modern world or the greater ease of publishing. It is as much a fact of cultural conditions as is the significant relation of rhetoric to the intense public mindedness of classical men, the relative insignificance of tragedy in a thoroughly Christianized world view, the disappearance of epic from a nonaristocratic world, or the powerful assertion of the novel in an age of burghers. The usage of the term "autobiography" itself is suggestive, although this mode of historical explanation is always defective in the sense that such older terms as "hypomnemata," "commentarii," "vita," "confessions," or "memoirs" may well have covered the functions subsequently encapsulated in a newly fashionable term. In German the term makes its appearance shortly before 1800; the Oxford English Dictionary attributes first English usage to Southey in an article on Portuguese literature from the year 1809. It is the intent of this paper to argue the thesis that the autobiographic genre took on its full dimension and richness when Western Man acquired a thoroughly historical understanding of his existence. Autobiography assumes a significant cultural function around A.D. 1800. The growing significance of autobiography is thus a part of that great intellectual revolution marked by the emergence of the particular modern form of historical mindedness we call historism or historicism.