rest to motion, were confronted by a riddle; for consciousness like motion cannot come into being all at once. The relation of the unconscious to consciousness is analogous to the relation of rest and motion. In order to vindicate the continuity of soul-life, Leibnitz directs attention to the fine nuances and changes of consciousness which are frequently overlooked. We are likewise obliged to postulate such minimal elements (petites perceptions) in the unconscious.
Leibnitz first elaborated this, his so-called theory of Monads, in a short essay in 1685 (Petit discours de metaphysique) and in his correspondence with Arnauld during the following year, but not until he had prepared the way for it by a number of earlier essays. He afterwards published several expositions of the theory especially in the Système nouveau (1695) and in the Monadologie (1714).—Leibnitz approaches his system first by the method of analysis, and then by the method of analogy. He seeks the ultimate presuppositions of science and then explains these presuppositions by means of analogy. Here he made a very important discovery, in showing that analogy is the only method by which to construct a positive metaphysics. Every mythology, religion and metaphysical system had used this method; but Leibnitz is the first to understand the principle which forms its basis. His system, the first attempt at a metaphysical idealism (i.e. the theory that the fundamental principle of reality is spiritual) since Plato and the pattern of all later idealistic attempts, has, to say nothing of its content, a permanent interest just because of this clear consciousness of its source. However if we should ask him why he uses the principle of analogy with so much assurance, he would answer: Because its help offers