John Locke (1632-1704) was educated at Christ Church, Oxford and held various academic posts at that university, lecturing on Greek and rhetoric. An English philosopher and physician, he is widely regarded as one of the most influential of Enlightenment thinkers and commonly known as the "Father of Liberalism." He wrote also on theology, education, and in defence of religous tolerance, while founding the analytic philosophy of the mind.
David Hume (1711-1776) was a Scottish philosopher, historian, economist, and essayist, who is best known today for his highly influential system of radical philosophical empiricism, skepticism, and naturalism. As well as his Essays, which were republished and expanded throughout his life, he wrote A Treatise of Human Nature.
George Berkeley (1685-1753) was an Irish philosopher best known for the advancement of a theory he called "immaterialism." He wrote A Treatise Concerning the Principles of Human Knowledge in 1710.