DESCARTES TO BERKELEY In 1714 two of Leibniz’s most important short treatises appeared: the Monadology and The Principles of Nature and of Grace The Monadology contains a developed and polished form of the system adumbrated in the Discourse Whatever is complex, it argues, is made up of what is simple, and whatever is simple is unextended, for if it were extended it could be further divided But whatever is material is extended, hence there must be simple immaterial elements These soul-like entities Leibniz called monads—these are the ‘worlds apart’ of the Discourse Whereas for Spinoza there was only one substance, with the attributes of both mind and extension, for Leibniz there are inWnitely many substances, with the properties only of souls Like Malebranche, Leibniz denied that creatures could be causally aVected by other creatures ‘Monads’, he said, ‘have no windows, by which anything could come in or go out.’ Their life is a succession of mental states or perceptions, but these are not caused by the external world A monad mirrors the world, not because the world shines into it, but because God has programmed it to change in synchrony with the world A good clockmaker can construct two clocks which will keep such perfect time that they forever strike the hours at the same moment In relation to all his creatures, God is such a clockmaker: at the very beginning of things he pre-established the harmony of the universe In the same year as Leibniz wrote the Monadology, Queen Anne of Britain died The British Act of Settlement of 1701 had settled the succession on the heirs of Sophie, the Electress of Hanover, and her son, the Elector Georg Ludwig, became King George I of England Leibniz did not follow his employer to London but was left behind in Hanover He might well have been unwelcome in England, because of his quarrel with Newton over the ownership of the inWnitesimal calculus The Royal Society had intervened in the dispute and awarded the priority to Newton in 1712 Leibniz died in 1716, leaving behind a mass of unpublished papers and a number of incomplete projects, the most ambitious of which was a comprehensive encyclopedia of human knowledge This was to be the combined work of religious orders, such as the Benedictines and the Jesuits, and the recently founded learned societies, such as the Royal Society, the Acade´mie des Sciences in Paris, and the Prusssian Academy of which Leibniz had himself been the Wrst president Nothing came of the project, and now, 75