Sir Isaac Newton (January 4, 1643 - March 31, 1727), an English mathematician, physicist, astronomer, alchemist, and natural philosopher who is generally regarded as one of the greatest scientists and mathematicians in history. Newton wrote the Philosophiae Naturalis Principia Mathematica, in which he described universal gravitation and the three laws of motion, laying the groundwork for classical mechanics. Among other scientific discoveries, Newton built the first practical reflecting telescope and developed a theory of colour based on the observation that a prism decomposes white light into the many colours that form the visible spectrum. He also formulated an empirical law of cooling and studied the speed of sound and the origin of stars. Newton played a major role in the development of calculus, sharing credit with Gottfried Leibniz. Newton was known to be highly religious and during his lifetime actually wrote more on Biblical hermeneutics and occult studies than on science and mathematics, the subjects he is mainly associated with.