British empiricism, though it was not a term used at the time, derives from the 17th century period of early modern philosophy and modern science. The term became useful in order to describe differences perceived between two of its founders Francis Bacon, described as empiricist, and René Descartes, who is described as a rationalist. Thomas Hobbes and Baruch Spinoza, in the next generation, are often also described as an empiricist and a rationalist respectively. John Locke, George Berkeley, and David Hume were the primary exponents of empiricism in the 18th century Enlightenment, with Locke being the person who is normally known as the founder of empiricism as such.