Throughout the nineteenth century evolution theory and the possibility of reconciling
it with Christian doctrine was a matter for free discussion among Catholics, but suddenly towards
the end of the century the attitude of the Roman doctrinal authorities hardened. Nothing public
was done but theologians, upon hearing that their theses had been examined in Rome and judged
to be untenable, began to withdraw their books from sale, make public retractions and cease to
discuss the subject. What processes lay behind these events, and who were the main persons
responsible for what was effectively a U-turn in the official church attitude of Pope Leo XIII's
pontificate, are questions that have been unanswerable until now. However, in 1998 the archives
of the Holy Office, now renamed the Congregation for the Doctrine of the Faith, were opened to
scholars so that it has become possible to clarify these particular mysteries. This article does that
for the first time, and the story it has to tell provides insights into the dynamics of cultural and
intellectual interactions within the Catholic Church community and with the rest of the world.
This Catholic story should be seen as something more than a struggle that took place within the
ranks of the Catholic Church: it was an episode in the history of science and its cultural relations
in the modern world.