42 INTRODUCTION 



changes in each Monad is different from that in every 

 other, and yet all are in harmony, the perfections of one 

 being accompanied by counterbalancing imperfections in 

 others. One Monad influences another ideally \ that is to 

 say, not db extra, but through an inner pre-established 

 conformity \ 



Relation of the System of pre-established Harmony to 

 Scholastic and Occasionalist Theories. 



Like most of the other doctrines of Leibniz, this system 

 of the pre-established harmony is a new hypothesis 

 devised to remedy the imperfections of previous theories. 

 The general problem which it is meant to solve appeared 

 at first for Leibniz in a particular form, that of the rela- 

 tions between soul and body. The usual pre-Cartesian 

 solution of this special problem was the theory of an 

 influxus physieus or actual passage of elements from the one 

 substance to the other. Descartes's complete separation 

 of soul from body, of thinking substance from extended 

 substance, was in total opposition to the earlier theory 3 . 



1 Monadology, 51. 



3 Cf. Nouveaux Essais, bk. iv. ch. 10, 10 (E. 376 a ; GL v. 421) : 

 1 As each of these souls expresses in its own way what takes place 

 outside of it, and is unable to have any influence upon other par- 

 ticular beings, or rather, as each must draw this expression entirely 

 from within its own nature, each soul must necessarily have received 

 this nature (or this internal ground of its expressions of what is 

 external) from a Universal Cause, upon which these beings are all 

 dependent, and which makes each of them to be perfectly in agree- 

 ment and in correlation with every other. This implies the use of 

 infinite knowledge and power and great ingenuity, especially with 

 reference to the spontaneous agreement of a mechanism with the 

 activities of the rational soul.' Also Monadology, 51 sqq. and 81 ; 

 New System, 14 and 15. 



3 CLTheodicee, Part i. 59 (E. 519 b ; G. vi. 135) : 'The scholastic 

 philosophers believed that there is a reciprocal physical interaction 

 between body and soul ; but since a thorough investigation has 

 shown that thought and extended mass have no connexion with 

 one another, and that they are created things which differ toto 

 genere, several modern writers have recognized that there is no 

 physical communication between soul and body, although there 

 always remains the metaphysical communication, which makes of 

 soul and body one and the same agent, or what is called one 

 person.' 



