Bishop of Cremona in Italy, who added an appendix to a book of his own, summarizing and recommending Zahm's views. Bonomelli too was pressured, and retracted his views in a public letter, also in 1898. Zahm, like St. George Jackson Mivart and his followers, accepted evolution, but not the key Darwinist principle of natural selection, which was still a common position among biologists in general at the time. Another American Catholic author William Seton accepted natural selection also, and was a prolific advocate in the Catholic and general press. Pope Pius IX On the Origin of Species was published in 1859, during the papacy of Pope Pius IX, who defined dogmatically papal infallibility during the First Vatican Council in 1869–70. The council has a section on "Faith and Reason" that includes the following on science and faith: On God the Creator, the First Vatican Council was very clear. The definitions preceding the "anathema" (as a technical term of Catholic theology, let him be "cut off" or excommunicated, cf. Galatians 1:6–9; Titus 3:10–11; Matthew 18:15–17) signify an infallible doctrine of the Catholic Faith (De Fide): According to Catholic theologian Dr. Ludwig Ott in his 1952 treatise Fundamentals of Catholic Dogma, it is to be understood that these condemnations are of the errors of modern materialism (that matter is all there is), pantheism (that God and the universe are identical), and ancient pagan and gnostic-manichean dualism (where God is not responsible for the entire created world, since mere "matter" is evil not good, see Ott, page 79). The First Vatican Council also upholds the ability of reason to know God from his creation: Popes Leo XIII and Pius X Pope Leo XIII, who succeeded in 1878, was known to advocate a more open approach to science, but also to be frustrated by opposition to this within the Vatican and leading church circles, "lamenting on a number of occasions, and not in a particularly private way, the repressive attitudes to scholars exhibited by people around him, and among those he clearly included members of La Civiltà Cattolica college of writers". On one occasion there was "quite a scene when the Pope energetically refused to have the writings of Mons. D'Hulst of Paris put on the Index of Forbidden Books". Providentissimus Deus, "On the Study of Holy Scripture", was an encyclical issued by Leo XIII on 18 November 1893 on the interpretation of Scripture.