72 INTRODUCTION 



with the principle of sufficient reason that nothing 

 should exist where something is possible ; for the prin- 

 ciple of sufficient reason requires the existence of a 

 complete world, that is to say, of that entire system of 

 compossible things which contains the fullest reality or 

 the greatest amount of essence l . Consequently the law 

 of continuity derives its force from the principle of 

 sufficient reason. And thus, in general, Leibniz's solu- 

 tion of his main problem is accomplished by the com- 

 bination of the principles of contradiction and sufficient 

 reason, giving, on the one hand, real units of substance, 

 even more thoroughly impenetrable and indivisible than 

 physical atoms ; and, on the other hand, in consistency 

 with these, a real whole, which is not a mere aggregate 

 of independent and perhaps mutually contradictory ele- 



i cf Iv me LMre ^ Qfafo ( I ^ I 6), Apostate (E. 758 b ; G. vii. 378) 

 (Clarke's translation) : ' In like manner, to admit a vacuum in 

 nature is ascribing to God a very imperfect work ; 'tis violating 

 the grand principle of the necessity of a sufficient reason ; which 

 many have talked of, without understanding its true meaning. . . . 

 To omit many other arguments against a vacuum and atoms, I shall 

 here mention those which I ground upon God's perfection and 

 upon the necessity of a sufficient reason. I lay it down as a prin- 

 ciple that every perfection which God could impart to things 

 without derogating from their other perfections has actually been 

 imparted to them. Now let us fancy a space wholly empty.' God 

 could have placed some matter in it, without derogating in any 

 respect from all other things ; therefore He hath actually placed 

 some matter in that space : therefore there is no space wholly 

 empty : therefore all is full. ... I shall add another argument, 

 grounded upon the necessity of a sufficient reason. 'Tis impossible 

 there should be any principle to determine what proportion of 

 matter there ought to be, out of all the possible degrees from 

 a plenum to a vacuum, or from a vacuum to a plenum.' [? The pro- 

 portion of either plenum to vacuum or of vacuum to plenum.'] ' Perhaps 

 it will be said that the one should be equal to the other; but, 

 because matter is more perfect than a vacuum, reason requires that 

 a geometrical proportion should be observed, and that there should 

 be as much more matter than vacuum as the former deserves to 

 have the preference before the latter. But then there must be no 

 vacuum at all ; for the perfection of matter is to that of a vacuum as 

 something to nothing.' Cf. also the beginning of Leibniz's second 

 letter (,E. 748 b ; G. vii. 356) : The more matter there is, the more 

 opportunity is there for God to exercise His wisdom and His power ; 

 and for this reason, among others, I hold that there is absolutely 

 no void.' , 



