24 INTRODUCTION 



logical development of the principles involved in the 

 position of Descartes 1 . In this connexion it is Descartes's 

 special theories that Leibniz has mostly in view, although 

 his arguments are equally applicable to the more thorough 

 metaphysic of Spinoza. ' Spinoza,' he tells us, 'has done 

 nothing but cultivate certain seeds of the philosophy of 

 M. Descartes 2 .' Descartes endeavoured to reach absolute 

 metaphysical certainty by a method which was after- 

 wards more clearly and fully applied by Spinoza, who 

 denned it in his great principle that l Determination is 

 negation/ The essence of Descartes's method of doubt 

 is the endeavour to attain certainty by stripping from 

 experience (as it is given in common consciousness) all 

 specific qualities or determinations, on the ground that 

 no contradiction in terms is involved in regarding each of 

 these qualities by itself as non-existent or other than it 

 is. The result of the method is to give, as the residual 

 ultimate certainty, nothing but the instrument by which 

 the process of stripping has been carried out, viz. the 



1 ' Cartesianae disciplinae intemperantia Spinozae doctrinam par it ; in 

 hoc sententia totum reperire est Leibnitium ' (Lemoine, Quid sit materia 

 apud Leibnitium, p. 52). ; The philosophy of Descartes . . . seems to 

 lead straight to the opinions of Spinoza, who dared to say what 

 Descartes carefully avoided.' (G. iv. 3464) 



a Lettre a I' Abbe Nicaise (1697) (E. 139 h; G. ii. 563). Leibniz, 

 especially in his earlier days, recognized that his philosophy had 

 much in common with that of Spinoza., although, as time went on, 

 it became more and more evident to him that they were funda- 

 mentally at variance. Thus, in an early letter (February, 1678), we 

 find Leibniz writing: 'I find in it' [the Ethics] 'plenty of fine 

 thoughts agreeing with mine, as is known to some of my friends 

 who are also friends of Spinoza. But there are also paradoxes 

 which seem to me unreal and not even plausible. As, for example, 

 that there is only one substance, namely God ; that created things 

 are modes or accidents of God ; that our mind has no wider outlook 

 [nihil amplius percipere~\ after this life ; that God Himself thinks 

 indeed, but nevertheless neither understands nor wills , that all 

 things happen by a certain necessity of fate ; that God acts not for 

 an end but by a certain necessity of nature, which is verbally to 

 retain, but really to give up, providence and immortality^; I regard 

 this book as a dangerous one for people -yrho will give themselves 

 the trouble to go deeply into it, for others do not care to under- 

 stand it.' Archivfur Geschichte d. Philosophic, vol. iii. p. 75. 



