John Locke was a 17th century British philosopher, physician, and government official. Some of his most influential works examined the limits of human understanding and advocated for religious tolerance. He is considered one of the earliest empiricists, arguing that knowledge comes from experience and senses rather than innate ideas. In his monumental work "An Essay Concerning Human Understanding," Locke laid out his empiricist view that the mind starts as a blank slate and ideas are built up from simple impressions of sensation and reflection.