Seventeen years ago, in a highly provocative article in this journal, E. C. Mossner rose to the defense of David Hume's historical writings, which had been treated with considerable severity by scholars such as J. B. Black, who, in his Art of History, had compared them unfavorably with those of his contemporaries, in particular Voltaire. Mossner, however, in trying to bring out the qualities of Hume's History of England, confronted it almost exclusively with Voltaire's Siècle de Louis XIV, and in this instance it must be admitted that Hume labored under a grave disadvantage, since his far more comprehensive subject was harder to master from the artistic as well as the scientific point of view than Voltaire's. In the present article we shall transfer the comparison from the Siècle to Voltaire's longest and most mature historical effort, the Essai sur les moeurs et l'esprit des nations, and this considerably changes our perspective, for here Voltaire is dealing with a similar and, if anything, more difficult theme. In this way a parallel may prove highly instructive in bringing out the excellences and weaknesses of the two historians respectively in their approach to comparable subjects and in the formulation of their philosophy of history. What makes comparisons particularly inviting is the circumstance that Voltaire's topic also includes Hume's, so that in numerous instances it is possible to examine the reaction of both writers to the same events and personalities. While our investigation of the resemblances and differences in the thought of these two outstanding representatives of the Enlightenment will stress some of the traits shared by most historians of their age, we shall also attempt to underline the more individual elements that emerge from their works.