recognized one god under the form of a fiery sphere, the soul of the world, but this idea is probably of later origin. The popular belief in gods was attributed by Democritus to the desire to explain extraordinary phenomena (thunder, lightning, earthquakes) by reference to superhuman agency.

5. Ethics.—Democritus’s moral system—the first collection of ethical precepts which deserves the name—strongly resembles the negative side of the system of Epicurus. The summum bonum is the maximum of pleasure with the minimum of pain. But true pleasure is not sensual enjoyment; it has its principle in the soul. It consists not in the possession of wealth or flocks and herds, but in good humour, in the just disposition and constant tranquillity of the soul. Hence the necessity of avoiding extremes; too much and too little are alike evils. True happiness consists in taking advantage of what one has and being content with it (see Ethics).

DEMOGEOT, JACQUES CLAUDE (1808-1804), French man of letters, was born in Paris on the 5th of July 1808. He was professor of rhetoric at the lycée Saint Louis, and subsequently assistant professor at the Sorbonne. He wrote many detached papers on various literary subjects, and two reports on secondary education in England and Scotland in collaboration with H. Montucci. His reputation rests on his excellent Histoire de la littérature française depuis ses origines jusqu’à nos jours (1851), which has passed through many subsequent editions. He was also the author of a Tableau de la littérature française au XVIIe siècle (1859), and of a work (3 vols., 1880-1883) on the influence of foreign literatures on the development of French literature. He died in Paris in 1894.

DEMOGRAPHY (from Gr. δῆμος, people, and γράφειν, to write), the science which deals with the statistics of health and disease, of the physical, intellectual, physiological and economical aspects of births, marriages and mortality. The first to employ the word was Achille Guillard in his Éléments de statistique humaine ou démographie comparée (1855), but the meaning which he attached to it was merely that of the science which treats of the condition, general movement and progress of population in civilized countries, i.e. little more than what is comprised in the ordinary vital statistics, gleaned from census and registration reports. The word has come to have a much wider meaning and may now be defined as that branch of statistics which deals with the life-conditions of peoples.

DEMOIVRE, ABRAHAM (1667-1754), English mathematician of French extraction, was born at Vitry, in Champagne, on the 26th of May 1667. He belonged to a French Protestant family, and was compelled to take refuge in England at the revocation of the edict of Nantes, in 1685. Having laid the foundation of his mathematical studies in France, he prosecuted them further in London, where he read public lectures on natural philosophy for his support. The Principia mathematica of Sir Isaac Newton, which chance threw in his way, caused him to prosecute his studies with vigour, and he soon became distinguished among first-rate mathematicians. He was among the intimate personal friends of Newton, and his eminence and abilities secured his admission into the Royal Society of London in 1697, and afterwards into the Academies of Berlin and Paris. His merit was so well known and acknowledged by the Royal Society that they judged him a fit person to decide the famous contest between Newton and G. W. Leibnitz (see Infinitesimal Calculus). The life of Demoivre was quiet and uneventful. His old age was spent in obscure poverty, his friends and associates having nearly all passed away before him. He died at London, on the 27th of November 1754.