In his Age of Louis XIV. he announced that his object was "to paint not the actions of a single man, but the mind of men (l'esprit des hommes) in the most enlightened age that had ever been," and that "the progress of the arts and sciences" was an essential part of his subject. In the same way he proposed in the Essay to trace "l'histoire de l'esprit humain," not the details of facts, and to show by what steps man advanced "from the barbarous rusticity" of the times of Charlemagne and his successors "to the politeness of our own." To do this, he said, was really to write the history of opinion, for all the great successive social and political changes which have transformed the world were due to changes of opinion. Prejudice succeeded prejudice, error followed error; "at last, with time men came to correct their ideas and learn to think." The motif of the book is, briefly, that wars and religions have been the great obstacles to the progress of humanity, and that if they were abolished, with the prejudices which engender them, the world would rapidly improve. "We may believe," he says, "that reason and industry will always progress more and more; that the useful arts will be improved; that of the evils which have afflicted men, prejudices, which are not their least scourge, will gradually disappear among all those who govern nations, and that philosophy, universally diffused, will give some consolation to human nature for the calamities which it will experience in all ages." This indeed is not the tone of the Abbe de Saint-Pierre. Voltaire's optimism was always tempered with cynicism. But the idea of Progress is there, though moderately conceived. And it is based on the same principle--universal reason implanted in man, which "subsists in spite of all the passions which make war on it, in spite of all the tyrants who would drown it in blood, in spite of the imposters who would annihilate it by superstition." And this was certainly his considered view. His common sense prevented him from indulging in Utopian speculations about the future; and his cynicism constantly led him to use the language of a pessimist. But at an early stage of his career he had taken up arms for human nature against that "sublime misanthrope" Pascal, who "writes against human nature almost as he wrote against the Jesuits"; and he returned to the attack at the end of his life. Now Pascal's Pensees enshrined a theory of life--the doctrine of original sin, the idea that the object of life is to prepare for death--which was sternly opposed to the spirit of Progress. Voltaire instinctively felt that this was an enemy that had to be dealt with. In a lighter vein he had maintained in a well-known poem, Le Mondain, [Footnote: 1756.] the value of civilisation and all its effects, including luxury, against those who regretted the simplicity of ancient times, the golden age of Saturn. O le bon temps que ce siecle de fer!