He was a learned theologian and manifested a reforming spirit. As an example, his papal bull of 15 November 1621, Aeterni Patris Filius, regulated papal elections, which henceforth were to be by secret ballot; three methods of election were allowed: by scrutiny, compromise and quasi-inspiration. On 6 January 1622, he established the Congregation for the Propagation of the Faith, the missionary arm of the Holy See. He was influential in bringing the Bolognese artist Guercino to Rome, a landmark in the development of the High Baroque style. He sat for his portrait busts, one of which was by Gian Lorenzo Bernini and by Alessandro Algardi, whose restrained bust in a tondo is in the Church of Santa Maria in Vallicella.
