'An Essay Concerning Human Understanding' is philosopher John Locke's pioneering examination of the origins of human knowledge and understanding. First published in 1690, it set the agenda for modern philosophy and influenced psychology and political theory. In 'An Essay Concerning Human Understanding. Volume Two' Locke discusses our use of language and its imperfections. He talks of the 'Abuse of Words' and laments the creation of words with no distinct meaning. The book also covers Locke's ideas on truth, judgement, probability, enthusiasm and reason. His radical theories on the nature of human knowledge and where it comes from went on to change the face of philosophy. Regarded as Locke's most powerful and important philosophical work, 'An Essay on Human Understanding' still resonates today.