The revival of Platonism in western Europe during the eleventh century inspired masters of cathedral schools to explore ways by which philosophy could serve as the handmaiden of theology. Yet some churchmen resisted such exploration, believing it had a subversive effect on Christian thought and morals. Among those who denounced the study of the philosophical tradition of classical antiquity was Manegold of Lautenbach. He aimed his fiery polemical tract, the "Liber contra Wolfelmum", at a master from Cologne who glorified the ancients while siding with the Holy Roman Emperor, Henry IV (1056-1106), against Pope Gregory VII (1073-1085) in the struggle known as the Investiture Controversy. Manegold did not oppose logic and philosophy per se, but rather their use in supporting a political program that questioned the authority of the pope and undermined the unity of Christendom.