The subject of my lecture is an appropriate one for several reasons. The first is purely chronological. Hume's first and greatest work, the Treatise of Human Nature, was published in 1739, two hundred years ago. Its illustrious author was then quite unknown in the world, and as he tells us himself the book “fell dead-born from the press.” But by the end of the eighteenth century its reputation was securely established, and it has long been regarded as one of the masterpieces of European thought, and as the classical statement of the Empiricist Philosophy. It is true that, like other classics, it has had its ups and downs. During the Absolute Idealist period, which ended early in the present century, Hume was the great bogey-man, and the duty of all self-respecting philosophers was to refute him. In our own day things are different. Empiricism, despite many obituary notices, is very much alive again. And this time it is in close alliance with Natural Science, and has equipped itself with all the technique of modern Symbolic Logic; it is more vigorous in construction and more formidable in criticism than it has ever been before. Consequently Hume is no longer the bogey-man. People now read the Treatise not as an awful warning, but as a source of stimulus and illumination. Incidentally, we can now enjoy his admirable style without any qualms. It is no longer thought that if a philosopher writes in clear and entertaining English, what he writes must therefore be either superficial or false. We regard obscurity and turgidity as demerits, not as signs of profound thinking. Moreover, we have learned to appreciate the eighteenth century, of which Hume was one of the most characteristic products.