harmony with it, an assumption which is expressed in the old rule: Entia præter necessitatem non esse multiplicanda. The law of Specification, on the other hand, is stated by Kant in these words: Entium varietates non temere esse minuendas. That is to say, we must carefully distinguish the species which are united under a genus, and the lower kinds which in their turn are united under these species; taking care not to make a leap, and subsume the lower kinds and individuals under the concept of the genus, since this is always capable of division, but never descends to the object of pure perception. Plato and Kant agree that these laws are transcendental, and that they presuppose that things are in harmony with them.
The previous treatment of the principle of sufficient reason, even by Kant, has been a failure, owing to the neglect of the second of these laws, It may well be that we shall find that this principle is the common expression of more than one fundamental principle of knowledge, and that the necessity, to which it refers, is therefore of different kinds. It may be stated in these words: Nihil est sine ratione cur potius sit, quam non sit. This is the general expression for the different forms of the assumption which everywhere justifies that question "Why?" which is the mother of all science.
CHAPTER II.
Schopenhauer in this chapter traces historically the forms in which the principle had been stated by his predecessors, and their influence. He points out that in Greek philosophy it appeared in two aspects – that of the necessity of a ground for a logical judgment, and that of a cause for every physical change – and that these two aspects were systematically confounded. The Aristotelian division, not of the forms of the principle itself, but of one of its aspects, the causal, exemplified a confusion which continued throughout the Scholastic period. Descartes succeeds no better. His proof of the existence of God that the immensity of His nature is a cause or reason beyond which no cause is needed for His existence, simply illustrates the gross confusion between cause
