Copernicus’s De revolutionibus was removed from the Index of Forbidden Books in 1758.
Nicolaus Copernicus published De revolutionibus orbium coelestium in 1543, presenting a mathematical model in which Earth and the other planets orbit the Sun. The book initially circulated among scholars, but its implications became increasingly controversial after Galileo’s telescopic discoveries and the Church’s 1616 condemnation of heliocentrism.
In 1616, De revolutionibus was suspended until corrected rather than simply destroyed or permanently banned. Church censors required changes to passages presenting heliocentrism as physical fact. The book remained available in corrected form to qualified readers, but the uncorrected edition stayed on the Index until 1758, when Pope Benedict XIV removed it from the revised list.
The year 1835 is another important date: Copernicus’s work and Galileo’s Dialogue were omitted from a later edition of the Index. That later date is sometimes confused with the 1758 removal, but 1758 is the answer for De revolutionibus’s removal from the Index.