THE age of the Enlightenment has a peculiar interest and value for the student of the history of philosophy. The philosophical output of this period is unusually rich and significant, embracing as it does the classical writings of Locke, Berkeley, Hume, Leibniz, Rousseau and Kant, and therefore may well be studied for the material which these separate contributions severally contain. But, more than this, the eighteenth-century philosophy is a period in which a great movement of thought is exhibited, and that, too, on a large and conspicuous stage. England, France, Germany form its settings. It begins with Locke and is completed in Kant. And whatever significance Kant may possess for the philosophical world to-day attaches also to this period, for this period served to open the way for the critical philosophy of the great master which is its appropriate culmination.