Unconquerable then as always, Voltaire devoted himself in prison to his literary ambitions, planning his Henriade and completing his OEdipe, which was produced in 1718 with signal success. Voltaire was thus already a distinguished young poet and dramatist when, in 1726, after enduring the affronts of an assault by a nobleman's lacqueys, and of imprisonment in the Bastille for seeking amends by duel, he came to England, where, like Deslandes before him, he met with a ready welcome from the freethinkers. [968] Four years previously, in the powerful poem, For and Against, [969] he had put his early deistic conviction in a vehement impeachment of the immoral creed of salvation and damnation, making the declaration, "I am not a Christian." Thus what he had to learn in England was not deism, but the physics of Newton and the details of the deist campaign against revelationism; and these he mastered. [970] Not only was he directly and powerfully influenced by Bolingbroke, who became his intimate friend, but he read widely in the philosophic, scientific, and deistic English literature of the day, [971] and went back to France, after three years' stay, not only equipped for his ultimate battle with tyrannous religion, but deeply impressed by the moral wholesomeness of free discussion. [972] Not all at once, indeed, did he become the mouthpiece of critical reason for his age: his literary ambitions were primarily on the lines of belles lettres, and secondarily on those of historical writing. After his Pour et Contre, his first freethinking production was the not very heretical Lettres philosophiques or Lettres anglaises, written in England in 1728, and, after circulating in MS., published in five editions in 1734; and the official burning of the book by the common hangman, followed by the imprisonment of the bookseller in the Bastille, [973] was a sufficient check on such activity for the time. Save for the jests about Adam and Eve in the Mondain (1736), a slight satire for which he had to fly from Paris; and the indirect though effective thrusts at bigotry in the Ligue (1723; later the Henriade); in the tragedy of Mahomet (1739; printed in 1742), in the tales of Memnon and Zadig (1747-48), and in the Idées de La Mothe le Vayer (1751) and the Défense de Milord Bolingbroke (1752), he produced nothing else markedly deistic till 1755, when he published the "Poem to the King of Prussia," otherwise named Sur la loi naturelle (which appears to have been written in 1751, while he was on a visit to the Margravine of Bayreuth), and that on the Earthquake of Lisbon. So definitely did the former poem base all morality on natural principles that it was ordered to be burned by the Parlement of Paris, then equally alarmed at freethinking and at Molinism. [974] And so impossible was it still in France to print any specific criticism of Christianity that when in 1759 he issued his verse translations of the Song of Solomon and