THE MONADOLOGY 219 



6. Thus it may be said that a Monad can only come 

 into being or come to an end all at once ; that is to say, 

 it can come into being only by creation and come to an 

 end only by annihilation, while that which is compound 

 comes into being or comes to an end by parts 7 . 



7. Further, there is no way of explaining how a 

 Monad can be altered in quality or internally changed 8 

 by any other created thing ; since it is impossible 

 to change the place of anything in it or to conceive 

 in it any internal motion which could be produced, 

 directed, increased or diminished therein, although all 

 this is possible in the case of compounds, in which 

 there are changes among the parts 9 . The Monads 

 have no windows, through which anything could come 

 in or go out. Accidents cannot separate themselves 

 from substances nor go about outside of them, as the 

 1 sensible species ' of the Scholastics used to do 10 . Thus 



7 Consider, by way of analogy and contrast, what Spinoza says 

 regarding the eternity of the human mind, Ethics, v. prop. 23. 

 Spinoza dispenses with the idea of creation. But according to 

 Leibniz there are created Monads, whose creation is, nevertheless, 

 not an event in time, for time and space have to do merely with 

 phenomena, and the Monads are not in time and space, but con- 

 dition them. Cf. 47 and Introduction, Part iii. p. 101. 



8 The meaning is that by other things the Monad can neither 

 be altered as to its nature, i.e. changed into something else, nor 

 even affected in those changes of state which it can undergo 

 without a change of nature. 



9 It is implied that all changes in bodies are reducible to traits- 

 position of parts, and ultimately to changes in the amount alid 

 direction of motion. See Introduction, Part iii. pp. 89 sqq.'' r 



10 Leibniz seems here to have in view partly the doctrines of 

 Thomas Aquinas and partly the scholastic theories which werer , 

 based on the system of Democritus. The l species ' are images or 

 immaterial representations of material qualities. According to 

 Thomas Aquinas, the accidents of things are known to us by 

 means of sensible species, or particular images, while we know 

 the essences of things by means of intelligible species or general I 

 images. The scholastic theory in general may be said to be t^ 

 the sensible or intelligible ' species ' in us have something 

 common with the accidents or essences in things, though 



