"Phenomenology" is, in the 20th century, mainly the name for a philosophical movement whose primary objective is the direct investigation and description of phenomena as consciously experienced, without theories about their causal explanation and as free as possible from unexamined preconceptions and presuppositions. The term itself is much older, going back at least to the 18th century, when Johann Heinrich Lambert, in his Neues Organon (1764), applied it to that part of his theory of knowledge which distinguishes truth from illusion and error. In the 19th century it became associated chiefly with Hegel's Phänomenologie des Geistes (1807), which undertook to trace the development of the human spirit from mere sense-experience to "absolute knowledge." The so-called Phenomenological Movement did not get under way until the first decade of the 20th century. But even this new phenomenology includes so many varieties that a fair picture requires a brief sketch of its development.