 The philosophical works by Leibniz that we typically consider today to represent his mature philosophical views were published posthumously. The Principles of Nature and Grace appeared in 1718, The Monadology in 1720, and the New Essays Concerning Human Understanding as late as 1765. Although the early Kant and later German thinkers had the benefit of these texts, Wolff had no such luxury when writing his German Metaphysics in 1719.