In March 1753, Voltaire left the court, thoroughly weary of life in a place where there was so little interest in letters. He had a fracas at Frankfort, where he was required to give up the court decorations he had worn with childlike enjoyment, and also a volume of royal verses which Frederick did not wish to be made public. For five weeks he lay in prison with his niece, Madame Denis, complaining of frightful indignities. He boxed the ears of a bookseller to whom he owed money, attempted to shoot a clerk, and in general committed many strange follies which were quite opposed to his claims to philosophy. There was an end of close friendship with Prussia, but he still drew his pension and corresponded with the cynical Frederick, only occasionally referring to their notorious differences. In dispraise of the niece Madame Denis, the King abandoned the toleration he had professedly extended. "Consider all that as done with," he wrote on the subject of the imprisonment, "and never let me hear again of that wearisome niece, who has not as much merit as her uncle with which to cover her defects. People talk of the servant of Molière, but nobody will ever speak of the niece of Voltaire."

The poet resented this contempt of his niece, for he was indulgently fond of the homely coquette who was without either wit or the good sense to win pardon for the frivolity of her tastes and extravagances. Living in a learned circle, she talked, like a parrot, of literature and wrote plays for the theatre of Ferney. "She wrote a comedy; but the players, out of respect to Voltaire, declined to act in it. She wrote a tragedy; but the one favour, which the repeated entreaties of years could never wring from Voltaire, was that he would read it."

In spite of his quarrels, Voltaire spoke favourably of the German freedom which allowed writings to be published reflecting on the Great Elector. He could not endure the hostile temper of his own land and deserted Paris to settle at Geneva, that free republic which extended hospitality to refugees from all countries. He built two hermitages, one for summer and one for winter, both commanding beautiful scenes, which he enjoyed for twenty years to come, though he was not content with one shelter. He bought a life-interest in Tournay and the lordship of Ferney in 1758, declaring that "philosophers ought to have two or three holes underground against the hounds who chase them." From Ferney he denounced the religion of the time, accusing the Church of hatred of truth and real knowledge, with which was coupled a terrible cruelty and lack of toleration.

To make superstition ridiculous was one of the objects of Voltaire's satire, for, in this way, he hoped to secure due respect for reason. All abuses were to be torn away, and such traditions as made slaves of the people. The shameful struggles between Jesuits and Jansenists were at their height. How could religion exist when one party believing in works denied the creed of a second believing grace better than deeds, and when both sides were eager to devote themselves to persecution?

In Voltaire's day, the condemnation of free writing came chiefly from the clergy. They would shackle the mind and bring it in subjection to the priesthood. Here was a man sneering at the power claimed by members of a holy body. The narrow bigotry of priests demanded that he should be held in bondage. Yet he did not mock at men who held good lives but at the corrupt who shamed their calling. The horrors of the Inquisition were being revived by zealous Jesuits who were losing authority through the increasing strength of another party of the Catholic Church, then known as Jansenists.

The Jansenists followed the doctrines of Calvin in their belief in predestination and the necessity for conversion, but they differed widely from the Protestants on many points, holding that a man's soul was not saved directly he was converted although conversion might be instantaneous. They were firmly convinced that each human soul should have personal relation with its Maker, but held that this was only possible through the Roman Church. Their chief cause of quarrel with the Jesuits was the accusation brought against the priests of that order that they granted absolution for sins much too readily and without being certain of the sinners' real repentance.

Voltaire's blood boiled when he heard that three young Protestants had been killed because they took up arms at the sound of the tocsin, thinking it was the signal for rebellion. He received under his protection at Geneva the widow and children of the Protestant Calas, who had been broken on the wheel in 1762 because he was falsely declared to have killed his son in order to prevent his turning Catholic. A youth, named La Barre, was sentenced, at the instance of a bishop, to have his tongue and right hand cut off because he was suspected of having tampered with a crucifix. He was condemned to death afterwards on the most flimsy evidence.

Voltaire was all aflame at the ignorance of such fanatics. There was laughter in the writings of the unbelievers of the time, but it was laughter inspired by the miserable belief that jesting was the only means of enduring that which might come. "Witty things do not go well with massacres," Voltaire commented. There was force in him to destroy, and he set about destruction.

The clergy had refused in 1750 to bear their share of taxation, though one-fifth of France was in their hands. Superstition inevitably tends to make bad citizens, the philosopher observed, and set forth the evils to society that resulted from the idle lives which were supported by the labour of more industrious subjects. But in his praiseworthy attack upon the spirit of the Catholicism of his day which stooped to basest cruelty, Voltaire appealed always to intelligence rather than to feeling. He wanted to free the understanding and extend knowledge. He set up reason as a goddess, and left it to another man to point the way to a social revolution.

Jean-Jacques Rousseau it was who led men to consider the possibility of a State in which all citizens should be free and equal. He suffered banishment and much hardship for the bold schemes he presented. The Parlement of Paris was ruthless when the two books—Émile and the Social Contract—were published in 1762.