A product of the Roman Inquisition, the Index Librorum Prohibitorum was an annually renewed list of books, journals, and other publications viewed as heretical by the Catholic Church. Viewed as a moral and spiritual safeguard against Protestantism, censorship of anti-clerical literature was enforced in the Papal States, where heretical books were not only outlawed, but sought out during domiciliary visits from the clergy. Each publication on the list was examined closely with the intention of finding an excerpt or a statement that could be interpreted as anti-Catholic (i.e. against the interests of the Church or the faith). Authors and readers of heretical publications—among them Galileo, whose “Dialogue Concerning the Two Chief World Systems” sparked controversy among Church officials—were tried by the Inquisition; punishment for such crimes ranged in severity from house arrest to imprisonment to execution. (Image Source: Jastrow (Own Work (Own Picture)) [Public Domain], via Wikimedia Commons, https://commons.wikimedia.org/w/index.php?curid=1193142)