Differently from the primary thanatism which originally characterized primitive man, and has always been widely spread, the _secondary_ absence of belief in immortality is only found at a late stage of history: it is the ripe fruit of profound reflection on life and death, the outcome of bold and independent philosophical speculation. We first meet it in some of the Ionic philosophers of the sixth century B.C., then in the founders of the old materialistic philosophy, Democritus and Empedocles, and also in Simonides and Epicurus, Seneca and Plinius, and in an elaborate form in Lucretius Carus. With the spread of Christianity at the decay of classical antiquity, athanatism, one of its chief articles of faith, dominated the world, and so, amid other forms of superstition, the myth of personal immortality came to be invested with a high importance. Naturally, through the long night of the Dark Ages it was rarely that a brave free-thinker ventured to express an opinion to the contrary: the examples of Galileo, Giordano Bruno, and other independent philosophers, effectually destroyed all freedom of utterance. Heresy only became possible when the Reformation and the Renaissance had broken the power of the papacy. The history of modern philosophy tells of the manifold methods by which the matured mind of man sought to rid itself of the superstition of immortality. Still, the intimate connection of the belief with the Christian dogma invested it with such power, even in the more emancipated sphere of Protestantism, that the majority of convinced free-thinkers kept their sentiments to themselves. From time to time some distinguished scholar ventured to make a frank declaration of his belief in the impossibility of the continued life of the soul after death. This was done in France in the second half of the eighteenth century by Voltaire, Danton, Mirabeau, and others, and by the leaders of the materialistic school of those days, Holbach, Lamettrie, etc. The same opinion was defended by the able friend of the Materialists, the greatest of the Hohenzollerns, the monistic "philosopher of Sans-souci." What would Frederick the Great, the "crowned thanatist and atheist," say, could he compare his monistic views with those of his successor of to-day?