Those in the book trade were not impervious to the ideas of the Lutheran Reformation that began to circulate in France in the mid-1520s. Conrad Resch, at the Ecu de Bâle, published the first French translation of a text by Martin Luther. He also employed Pierre Vidoue and Simon Dubois, two printers who supported the Reformation. Resch's successor, Chrétien Wechel, was also open to Lutheran ideas.
Between 1520 and 1530, however, it was not always possible to tell Catholics printers from Protestant ones. Many Catholics were won over to Reformation ideas but didn't want to completely break with the papacy. Moreover, many Protestants took pains to hide their religious preferences. Also, booksellers were above all merchants. Their editorial choices were dictated by the market, and did not necessarily represent their personal convictions.
By the early 1530s, booksellers and printers who were suspected of heresy became genuinely concerned about the Parlement de Paris and the Faculty of Theology.
By the early 1530s, booksellers and printers who were suspected of heresy became genuinely concerned about the Parlement de Paris and the Faculty of Theology. Although at first the sovereign tempered the censors' zeal, things changed abruptly in October 1534 in the wake of the Affair of the Placards. On the night of 17–18 October, placards (or posters) attacking the Catholic mass were put up in Paris and other cities in France. The response was swift in coming. On the 10th, 19th and 24th of December, a printer, a bookseller and a punch-cutter, Antoine Augereau, were burnt at the stake, all three accused of Lutheranism.
Some Parisian booksellers left France and set up shop along the country's borders, in Basel, Geneva, Strasbourg, Antwerp and Neuchatel, where they could ship Lutheran and Calvinist publications to France without risk. After the Sorbonne condemned Luther's teachings in April 1521, Conrad Resch became a citizen of Basle in 1522, before permanently abandoning Paris in 1526, when he sold the Escu de Basle to Chrestien Wechel. Later, after much pestering and threatening by the Faculty of Theology in Paris, the major printer-publisher Robert Estienne left Paris en 1550 and set up shop in Geneva.