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.