Ockham's principal works are: _Quaestiones et decisiones in quatuor libros sententiarum cum centilogio theologico_ (Lyons, 1495), [Footnote: I have met with a copy of this work amongst the incunabula in the possession of M. Olschki, of Venice. The printer's name is John Trechsel, who is described as _vir hujus artis solertissimus_.] _Summa logicae_ (Paris, 1483), _Quodlibeta_ (Paris, 1487), _Super potestate summi pontifia_ (1496). He died at Munich in 1343. The _Introductio ad Theologiam_ of the famous Abélard, another schoolman, was fatal to him. Abélard's name is more generally known on account of the golden haze of romance which surrounded him and the fair Heloise; and their loving letters have been often read and mourned over by thousands who have never heard of his theological writings. At one time the famous Canon of Notre Dame at Paris had an enthusiastic following; thousands flocked to his lectures from every country; his popularity was enormous. He combated the abuses of the age and the degeneracy of some of the clergy, and astonished and enraged many by the boldness of his speech and the novelty of his opinions. His views with regard to the doctrine of the Trinity expressed in his _Introductio_ (Traité de la Trinité) were made the subject of a charge against him, and certainly they cannot be easily distinguished from Sabellianism. The qualities or attributes of the Godhead, power, wisdom, goodness, were stated to be the three Persons. The Son of God was not incarnate to deliver us, but only to instruct us by His discourses and example. Jesus Christ, God and Man, is not one of the Persons in the Trinity, and a man is not properly called God. He did not descend into hell. Such were some of the errors with which Abélard was reproached. Whether they were actually contained in his writings, it is not so evident. We have only fragments of Abélard's writings to judge from, which have been collected by M. Cousin--_Ouvrages inédits d'Abélard_--and therefore cannot speak with certain knowledge of his opinions. At least they were judged to be blasphemous and heretical by the Council of Soissons, when he was condemned to commit his books to the flames and to retire to the Convent of St. Denys. Some years later, when he had recovered from the horrible mutilation to which he had been subjected by the uncle of Heloise, and his mind had acquired its usual strength, we find him at Paris, again attracting crowds by his brilliant lectures, and pouring forth books, and alas! another fatal one, _Sic et Non_, [Footnote: Petri Abelardi _Sic et Non_ (Marburgi, Sumptibus Librariae; Academy Elwertianae, 1851). The best edition of Abélard's letters is _P. Abaelardi et Heloisae conjugis ejus Epistolae, ab erroribus purgatae et cum codd. MSS. collatae cura Richardi Rawlinson, Londini, 1718, in-8_. There is also an edition published in Paris in 1616, 4to, _Petri Abelardi et Heloisae conjugis ejus, opera cum praefatione apologetica Franc. Antboësii, et