In 1559, Pope Paul IV published the first Index of banned books. "The index was a tool against the Reformation", explains priest and historian Hubert Wolf. As well as targeting theology books, the Vatican also censored scientists and philosophers, including most notoriously - Galileo. But many of the books submitted for censorship were passed. Hitler's 'Mein Kampf' was approved because "Hitler was already Chancellor and state authority was considered God-given." The list was finally abandoned in the late 60s but the Vatican still censors Catholic theologians who sway from the official line.