The Monadology

1. **The Monad, of which we shall here speak, is nothing but a simple substance, which enters into compounds. Simple, that is to say, without parts.**

2. **And there must be simple substances, since there are compounds; for a compound is nothing but a collection or aggregatum of simples.**

3. **Now where there are no parts, there can be neither extension nor form [figure] nor divisibility. These Monads are the real atoms of nature and, in a word, the elements of things.**

4. **No dissolution of these elements need be feared, and there is no conceivable way in which a simple substance can be destroyed by natural means.**

5. **For the same reason there is no conceivable way in which a simple substance might, through natural means, come into existence, since it cannot be formed by composition.**

6. **We may say then, that the existence of Monads can begin or end only through creation or annihilation, that is to say, it can begin only through creation and can end only through annihilation.**

7. **Monads are without windows, through which anything could come in or go out. Accidents cannot detach themselves nor can they stroll about outside of substances, as the 'sensible species' of the Scholastics used to do. Thus, neither substance nor accident can enter a Monad from without.**

8. **Nevertheless, Monads must have some qualities, otherwise they would not even be existing beings.**

9. **And if simple substances did not differ in quality, there would be absolutely no means of perceiving any change in things, for what is in the compound can come only from the simple ingredients, and Monads, if they have no qualities, differ only numerically, one Monad being distinguished from another only by internal movements which must differ from one another.**

10. **Each Monad, moreover, must be different from every other. For in nature there are never two beings, which are perfectly alike and in which it is not possible to find an internal difference, or at least a difference founded on an intrinsic quality [denomination].**

11. **Monads, having no parts, cannot be formed or fashioned but must exist all at once.**

12. **Thus their natural changes come from an internal principle, since an external cause can have no influence upon their inner being.**

13. **This internal principle of change is nothing other than appetite, by which it passes from one perception to another, by degrees which for us are imperceptible.**

14. **This passing from one perception to another may be brought about by a multitude of different ways; by the impression which an external object makes upon the senses, or by the memory of this impression, or by the soul's volition.**

15. **The perceptions in the Monad arise one from another by the laws of appetite or of the final causes of good and evil, which are physical points of view, and, according to this, the laws which cause the next perception to follow from the preceding, are called the laws of the series of perceptions.**