substitute to the secretary of the Superior General of the Jesuits (1843–56), John-Philip Roothaan, secretary (1856–62), consultor of the Congregation of the Index, and collaborator in the preparation of the Constitution De Fide Catholica of the First Vatican Council. He composed the first draft of the encyclical "Æterni Patris" of Pope Leo XIII on Scholasticism (1879). He played a leading part in the revival of Scholastic philosophy and theology. With the object of combating the doctrines of Georg Hermes, J. B. Hirscher, and Anton Günther, he composed his Theologie der Vorzeit (Theology of the Past) and Philosophie der Vorzeit (Philosophy of the Past), works which upon their appearance were pronounced in many quarters to be epoch-making. Convent of Sant'Ambrogio In 1856, Kleutgen alias Peters became confessor extraordinary to the franciscan Convent of St. Ambrose in Rome. The nuns of this convent honoured as a saint their founding abbess, Agnese Firrao (died 1854), although this had been forbidden by the holy office in 1816, which had convicted the abbess of "false sanctity", or pretending to be a saint. In 1858, the widowed Princess Katharina of Hohenlohe-Waldenburg-Schillingsfürst moved to Rome with the intention of becoming a nun. Her spiritual director, Cardinal Karl-August von Reisach, recommended that she join the Franciscan monastery of Sant’Ambrogio. Von Hohenzollern, having recently joined the convent as a novice, denounced its activities to an inquisition, accusing mistress of novices Maria Luisa, among others, of sexual transgressions, heretical practices and homicidal schemes. Maria Luisa claimed to receive messages from St. Mary, was performing rituals usually allowed only for priests, and slept with several of the novices. Other transgressions included affairs between the women and priests. When she challenged convent practices, Katharina became the victim of an attempted poisoning. As the investigation proceeded it emerged that Peters alias Kleutgen who as the "spiritual father" of the nuns had been entitled to hear confession in the convent and administer the sacrament of Penance had entered into sexual relations with Maria Luisa, whom he regarded as a saintly person given to visions and divine revelations. He had had knowledge of the poisoning of Katharina, although the degree to which he had instigated the attempted murder could not be ascertained. He was convicted as an heretic for his fostering of the cult of Agnese Firrao and sentenced to three years of house arrest. However Pope Pius IX reduced the sentence to two years,