At the turn of the century Martin Buber arrived on the philosophic scene. His path to maturity was one long struggle with the problem of unity--in particular with the problem of the unity of spirit and life--and he saw the problem itself to be rooted in the supposition of the primacy of the subject-object relation, with subjects "over here," objects "over there," and their relation a matter of subjects "taking in" objects or, alternatively, constituting them. But Buber moved into a position which undercuts the subject-object dichotomy and initiates a second "Copernican revolution" in philosophical thought.