If we estimate its course by literary works, or by social and political movements, we may distribute the history of it into two periods; one comprising the first half of the century, wherein it attacks the French church and Christianity; the other, the latter half, wherein it mingles itself with the demand for political change, and assaults the state,(516) until its effects are seen in the anarchy of the French revolution. In the former of these periods the unbelief is tentative and suggestive. About the time of the transition to the second, in the pride of supposed victory it becomes dogmatic. Christianity is supposed to be exploded. Philosophy seeks to occupy its place in the social and intellectual world. The early doubters and Voltaire mark the former of these epochs. Diderot and the French encyclopædists, with the ramification of their school at the court of Frederick II of Prussia, form the point of transition. Rousseau marks the opening of the second period, when unbelief was attempting to reconstruct society and remodel education. The selfish philosophy of Helvetius and his friends then carries on the course of the history of unbelief, until in the storm of the revolution it shows itself in the teaching of Volney, and the absurd acts of the theophilanthropists. The name of Voltaire, which the logical and chronological order introduces first to our notice, is so preeminent, that his character and teaching may express the history of the early movement in France. The story of his life, so far as we require now to be made acquainted with it, can be briefly told.(517) Born toward the close of the seventeenth century, he manifested, as a legend assures us, such a doubting spirit, even in boyhood, that his priestly preceptor predicted that he would prove a Coryphæus of deism. His rare precocity of intellect early acquired for him a reputation in the world of letters. Compelled to become an exile in England,(518) he studied its politics, its science, and its scepticism. On his return to France, he endeavoured to introduce among his countrymen the cosmical and mathematical doctrines of Newton; and made himself conspicuous in history, in poetry, in fiction, and above all, in theology, by his attacks on revealed religion and the French church. About the middle of the century, accepting an invitation to the court of Frederick the Great of Prussia, he aided thence the introduction of infidel doctrines in Germany. A few years later he withdrew into retirement at Ferney, but was able from his seclusion to wield an intellectual power throughout Europe. It was from this retirement that he denounced the acts of tyranny, or supposed injustice, inflicted by the French church. His indignant denunciations in the cases of the Sirven,(519) of La Barre,(520) and above all of the Calas,(521) gained for him the commendation and sympathy of Europe, and remain as monuments of the power of the pen.