Niccolo Machiavelli (3 May 1469 - 21 June 1527) was an Italian Renaissance diplomat, philosopher and writer, best known for The Prince. He has often been called the father of modern political philosophy and political science. For many years he served as a senior official in the Florentine Republic with responsibilities in diplomatic and military affairs. He wrote comedies, carnival songs, and poetry. His personal correspondence is of high importance to historians and scholars. He worked as secretary to the Second Chancery of the Republic of Florence from 1498 to 1512, when the Medici were out of power. John Locke was an English philosopher and physician, widely regarded as one of the most influential of Enlightenment thinkers and commonly known as the "father of liberalism". Thomas Hobbes (5 April 1588 - 4 December 1679), was an English philosopher, considered to be one of the founders of modern political philosophy. Hobbes is best known for his 1651 book Leviathan, in which he expounds an influential formulation of social contract theory. In addition to political philosophy, Hobbes contributed to a diverse array of other fields, including history, jurisprudence, geometry, the physics of gases, theology, and ethics, as well as philosophy in general.