The rest of the letters are mainly an attack on Jesuit casuistry. The Fifth Letter, published in a hurry after a police search in Jansenist-friendly publishing houses, is particularly dedicated to criticisms against the Jesuits' doctrine of moral probabilism, according to which one could adopt a "probable opinion", that is, an opinion made plausible by the authority of a theologian, even if it was less probable than another opinion – especially concerning what conduct ought to be followed, the nature of sins, etc. Pascal relied heavily on witty attack, composed of quotes from various books written by Jesuit casuists, in particular by Antonio Escobar y Mendoza's "Summula casuum conscientiae" (1627), which had enjoyed a great success, and also Thomas Sanchez, Vincenzo Filliucci (Jesuit and penitentiary at St Peter's), Antonino Diana, Paul Laymann, Etienne Bauny, Louis Cellot, Valerius Reginaldus, Bernard Lamy (censored on 8 October 1649 by the Faculty of Leuven for his defense of homicide), etc.