Censorship makes new ideas less available to others, but also reduces the number of people choosing to develop non-compliant ideas. We propose a new method to measure the effect of censorship on knowledge growth, accounting for the agents’ choice between compliant and non-compliant occupations. We apply our method to the Catholic Church’s censorship of books written by members of Italian universities and academies over the period 1400-1750. We highlight new facts: once censorship was introduced, censored authors were of better quality than the non-censored authors, but this gap shrank over time, and the intensity of censorship decreased over time. We use these facts to identify the deep parameters of a novel endogenous growth model that links censorship to knowledge diffusion and occupational choice. We conclude that the average log publication per scholar in Italy would have been 43% higher if censorship had not been present, while the effect of adverse macroeconomic processes is almost four times smaller. The induced reallocation of talents towards compliant activities explains half the effect of censorship.