William Paley (1743–1805) argues for the existence of God as the intelligent creator of the world in this, his last book, published in 1802. He builds on early modern natural theology including the works of John Ray, William Derham, and Bernard Nieuwentyt, and most of his examples are taken from medicine and natural history. Paley uses analogy and metaphors, including a particularly well-written version of the 'watchmaker analogy', to prove that the world is designed and sustained by God. This sixth edition also contains a detailed bibliography, appendices on Paley's courses, and background notes on key figures. It was an influential best-seller throughout the nineteenth century, read by theologians and scientists alike, and reprinted in cheap editions for the middle classes. It inspired many nineteenth-century works on natural theology, including the Bridgewater Treatises (which also appear in this series), and is a landmark of Western thought.