In 1439, the Council of Basel decreed that the doctrine of the Immaculate Conception must be held by all orthodox Catholics. The divines of the Sorbonne, in 1497, issued an order referring to the above decree and instructing that each candidate for the doctorate must be prepared to maintain this doctrine. The decree of the council was naturally not confirmed in Rome, but in 1483, a Bull of Sixtus IV condemned the contention that the doctrine of the Immaculate Conception is heretical and that the observance of the festival instituted under this name is in itself sinful. At the same time, however, he prohibits the declaring of the contrary doctrine as in itself heretical. In 1661, a Bull of Alexander VII says, while confirming the approval given by his predecessors to the doctrine, that it is not to be permitted to charge with heresy or with mortal sin those who have not accepted this doctrine, as the Church universal and the Holy Chair are not yet prepared to decide all the difficulties involved. In 1708, Clement XI declares that the festival of the Immaculate Conception is to be universally observed, but in the same year he orders to be confiscated and prohibited a reprint of the Bull in which this festival was first instituted. Gregory VII was the first Pope who permitted the term Immaculate Conception to find place in the Book of the Mass and to have included in the Laurentian Litany the words _Regina sine labe originali concepta_. In 1854, the doctrine of the Immaculate Conception is confirmed by Pius IX as a dogma of the Church. Through some oversight, the _Decretum Gen._, ii, 2, continued, however, to find place in the Index that was published in 1854. In December, 1854, is printed in connection with the publication of the _Decreta_ a declaration in substance as follows: “As the dogma of Immaculate Conception has now been authoritatively defined, works which treat of the same and which have in previous years been placed in the Index, are now to be eliminated from the Index, unless it may be that certain of these works are entitled to condemnation on grounds other than their conclusions in regard to this doctrine.” It appears therefore that no prohibition now rests upon books, whether placed on the earlier Indexes or not, which make defence of the doctrine. The first important book written in defence of the doctrine of the Immaculate Conception which was formally condemned, was the work of the Italian Capucin, J. O. Maria Zamora, _De eminentissimae Deiparae V. M. perfectione_, published in Venice in 1629 and placed on the Index in 1636. The list of prohibitions of the works of this group during the succeeding half-century is very considerable. I will note here but one additional title, _Quatres Sonnets à l’honneur de la très-pure et très-immaculée conception de la Vierge Marie_, by le Père Anne Joachim de Jésus-Marie.