GENERAL PRINCIPLES 67 



philosophy of Leibniz, each having its specific function, 

 but neither reducible to the other, while no attempt is 

 made to find a more comprehensive principle which may 

 include both. There are certain eternal and necessary 

 truths which are independent of the will of God, existing 

 in His understanding alone, and these are subject to the 

 principle of contradiction ; but the reality of all indi- 

 vidual substances and their changes is dependent on the 

 will as well as the understanding of God, and they are 

 all subject to the principle of sufficient reason. Each 

 principle expresses a certain necessity ; but the necessity 

 of the principle of contradiction differs in kind from 

 that of the principle of sufficient reason, the former 

 being an absolute, compelling, or metaphysical necessity, 

 whose opposite is impossible, involving self-contradiction, 

 while the latter is a relative, inclining, or moral neces- 

 sity, whose opposite is not impossible, but incompossible, 

 inconsistent not with itself but with the system of which 

 it is a part, inconsistent not so much with the eternally 

 true as with the best possible. 



The leading Characteristics of Leibniz" s Philosophy as 

 Results of the two great logical Principles. 



We are now in a position to see how the main features 

 of the Metaphysics of Leibniz are determined by these 

 great logical principles which underlie it \ The principle 

 of contradiction, taken by itself, is a principle of exclu- 

 sion. A is A (every real thing is identical with itself) 

 at all times, in all circumstances, throughout all changes, 

 in every variety of relations. Strictly speaking, then, 

 A can never become B. A is always A, B is always B ; 

 each is for ever exclusive of the other. ' Black is black, 

 furieusement black ; white is white, furieusement white. ' 

 The principle of contradiction, as thus interpreted, is 



1 What follows is, of course, not an exposition of Leibniz's explicit 

 doctrine, but an analytic investigation of the way in which his 

 logical principles fix the main lines of his philosophy. 



F 2 



