regarding the heliocentrism of the solar system, Johannes Kepler's (1571–1630) three laws of planetary motion, and Isaac Newton's (1642–1727) law of universal gravitation—laws of gravitation and of motion, and notions of absolute space and time—all combined to establish the regularities of heavenly and earthly bodies". Simultaneously, the development of machine technology and the emergence of the mechanical philosophy encouraged mechanical imagery unlikely to have come to the fore in previous ages. With such a backdrop, "deists suggested the watchmaker analogy: just as watches are set in motion by watchmakers, after which they operate according to their pre-established mechanisms, so also was the world begun by God as creator, after which it and all its parts have operated according to their pre-established natural laws. With these laws perfectly in place, events have unfolded according to the prescribed plan." For Sir Isaac Newton, "the regular motion of the planets made it reasonable to believe in the continued existence of God". Newton also upheld the idea that "like a watchmaker, God was forced to intervene in the universe and tinker with the mechanism from time to time to ensure that it continued operating in good working order". Similarly to Newton, René Descartes (1596–1650) speculated on "the cosmos as a great time machine operating according to fixed laws, a watch created and wound up by the great watchmaker". William Paley Watches and timepieces have been used as examples of complicated technology in philosophical discussions. For example, Cicero, Voltaire and René Descartes all used timepieces in arguments regarding purpose. The watchmaker analogy, as described here, was used by Bernard le Bovier de Fontenelle in 1686, but was most famously formulated by Paley. Paley used the watchmaker analogy in his book Natural Theology, or Evidences of the Existence and Attributes of the Deity collected from the Appearances of Nature, published in 1802. In it, Paley wrote that if a pocket watch is found on a heath, it is most reasonable to assume that someone dropped it and that it was made by at least one watchmaker, not by natural forces: Paley went on to argue that the complex structures of living things and the remarkable adaptations of plants and animals required an intelligent designer. He believed the natural world was the creation of God and showed the nature of the creator. According to Paley, God had carefully designed "even the most humble and insignificant organisms" and