The general view of scholars is that the Kabbalah had no appreciable influence on the philosophy of Gottfried Wilhelm Leibniz. But on the basis of new evidence, Professor Coudert argues that this conclusion is mistaken. Leibniz was neither the foolish optimist Voltaire made him out to be in Candide nor the supreme rationalist described by so many subsequent scholars. He was a radical gnostic, whose philosophy was profoundly influenced by the Lurianic Kabbalah. Once this somewhat startling fact is understood, key areas of his philosophy, such as his concept of monads, defence of free will, and theodicy, can be seen in entirely new ways, which solve many of the problems that have perplexed scholars. This book is for all levels of readers, from those with a general interest in intellectual history to specialists in philosophy, the history of science, theology, and Jewish studies.