This work, published in 1690, was a meticulous analysis of how knowledge becomes consolidated in the mind. Although excited by Locke’s ‘essay’, Leibniz harboured some reservations and subsequently penned a brief critique. Unfortunately, Locke took a very dim view of Leibniz’s personal communication and chose to ignore it. Still convinced that his critique was sound, Leibniz wondered if Locke might have simply misunderstood what he had written. So, in the interests of clarity, he expanded his arguments to fill a book – New Essays on Human Understanding. But just as Leibniz completed it, Locke died. Disinclined to challenge an adversary who suffered from the considerable handicap of being dead, Leibniz sportingly decided not to publish; however, his New Essays did finally appear in 1765, almost fifty years after his own death. New Essays is of major importance, not only because it contains a well-argued response to Locke but also because it contains the first significant entry into philosophical discussion of unconscious mental operations.
