mathematical hypothesis, to facilitate the explanation of certain natural phenomena. Besides this, the “Dialogues on the Two Principal Systems” had to be preceded by the sentence on and recantation of Galileo, as well as by an Essay “On the System of the Universe of the Ancient Hebrews,” by Calmet, in which the passages of Scripture bearing on the order of the world were interpreted in the traditional Catholic fashion.[610] The celebrated French astronomer Lalande, as he himself relates,[611] tried in vain when at Rome, in 1765, to get Galileo’s works expunged from the Index. The Cardinal Prefect of the Congregation of the Index objected that there was a sentence of the Congregation of the Holy Office in existence which must first be cancelled, but this was not done, and all remained as before; and even in the edition of the Index of 1819, strange to say, the five works mentioned above were to be found as repudiated by the Roman curia! It then happened in the following year, 1820, that Canon Joseph Settele, professor of optics and astronomy at the Archive-gymnasium at Rome, wrote a lesson book, “Elementi d’astronomia,” in which the Copernican system, in accordance with the results of science, was treated _ex professo_. The Master of the Palace, Philip Anfossi, to whom in his capacity of chief censor of the press the book was submitted, demanded under appeal to the decree of 5th March, 1616, still in force, that the doctrine of the double motion should be only treated hypothetically, and refused the _imprimatur_ until the MS. had been altered. Canon Settele, however, was not disposed to make himself ridiculous in face of the whole scientific world by compliance with these antiquated conditions, and appealed to Pope Pius VII., who referred the matter to the Congregation of the Holy Office. Here at last some regard was had to the times, and in the sitting of 16th August, 1820, it was decided that Settele might treat the Copernican system as established, which was approved by Pius VII. without hesitation. Father Anfossi could not, after this decision, prevent the work from publication as it was, but he resolutely pointed out the contradiction between this permission and the decree of 5th March, 1616, and published a treatise entitled: “Can any one who has made the Tridentine Confession, defend and teach as a thesis, and as an absolute truth and not a mere hypothesis, that the earth revolves and the sun is stationary?”[612] This gave rise to discussions in the College of Cardinals of the Holy Inquisition as to the attitude to be adopted by ecclesiastical authority towards the Copernican system, which had been universally adopted for more than a century. In the sitting of 11th September, 1822, they finally agreed, with express reference to the decree of the Index Congregation of 10th May, 1757, and 16th August, 1820, “that the printing and publication of works treating of the motion