Summa Theologica, by St. Thomas Aquinas, , at sacred-texts.com
After writing these few questions of the treatise on Penance, St. Thomas was called to the heavenly reward which he had merited by writing so well of his Divine Master. The remainder of the Summa Theologica, known as the Supplement, was compiled probably by Fra Rainaldo da Piperno, companion and friend of the Angelic Doctor, and was gathered from St. Thomas's commentary on the Fourth Book of the Sentences of Peter Lombard. This commentary was written in the years 1235-1253, while St. Thomas was under thirty years of age. Everywhere it reveals the influence of him whom St. Thomas always called the Master. But that influence was not to be always supreme. That the mind of the Angelic Doctor moved forward to positions which directly contradicted the Master may be seen by any student of the Summa Theologica. The compiler of the Supplement was evidently well acquainted with the commentary on the Sentences, which had been in circulation for some twenty years or more, but it is probable that he was badly acquainted with the Summa Theologica. This will be realized and must be borne in mind when we read the Supplement, notably TP, Q, A; also Q, A, ad 2 of the Supplement.