Leibniz, a central figure in the European Enlightenment, is known for several works: his Theodicy (1710), for which he was often accused (including by Voltaire) of advocating a mindless optimism in this, the "best of all possible worlds"; and his Monadology (1714), a theory of substance which grounded matter in entities he called "monads." He was a critic of John Locke's notion of the mind as a tabula rasa. Leibniz was also a prominent mathematician, and developed calculus independently of Sir Isaac Newton, for which he was accused of plagiary by the Royal Society -- a charge of which modern critics have acquitted him.
Wollstonecraft quotes from the Preface to his Theodicy.