GENERAL PRINCIPLES 35 



perception \ Similarly, the Monad has appetition, but 

 not necessarily in The sense of conscious desire or will. 4 

 As the essence of perception is multiplicity in unity, so 

 the essence of appetition is change jwithin the identity 

 or permanence of a simple substance. Appetition is ' the ^ 

 action of the internal principle which produces change 

 or passage from one perception to another 2 .' As the 

 Monads alone are real, every change in nature must be 

 change within a Monad. This change, as we have seen, 

 must be the unfolding of the whole which the Monad 

 potentially contains or represents. That is to say, it 

 must be the passing from one perception (or state of 

 representation, whether conscious or unconscious) to 

 another. And thus, wherever there is change there is 

 appetition. It is simply another name for the spon- 

 taneity of the Monad, its power of unfolding its whole 

 nature and experience from within itself. The Monad 

 as perceptive is thus a universal within, rather than 

 exclusive of, the particular, while as appetitive it is 

 dynamic and not static 3 . 



1 Cf. p. 135. Also Epistola ad E. C. Wagnerum (1710) (E. 466 a ; ' 

 G. vii. 529) : l This correlation of the internal and external, or 

 representation of the external in the internal, of the compound in 

 the simple, of multiplicity in unity, really constitutes perception.' 

 In a letter to Arnauld (1687) (G. ii. 112) Leibniz says that 'ex- 

 pression is a genus of which natural perception, animal feeling, 

 and intellectual knowledge are species. In natural perception 

 and feeling, it is enough that what is divisible and material, and 

 is actually dispersed among several beings, be expressed or repre- 

 sented in a single indivisible being or in substance which has 

 a genuine unity.' 



a Monadology, 15. 



3 'We could not say in what the perception of plants consists, 

 and even that of animals is not well conceived by us. Yet, 

 according to the general sense I give to these words, in order that 

 there may be a perception, it is enough that there should be 

 a variety in unity ; and in order that there may be appetition it is 

 enough that there should be a tendency to new perceptions.' 

 Letlre a Bourguet (1715) (E. 732 b ; G. iii. 581). ' The soul has 

 perceptions and appetitions, and its nature consists in these. 

 And as in body there are understood to be avrnvma. and figure of 

 some kind, although we do not know what are the figures of 

 imperceptible bodies ; so in the soul there are understood to be 



