From the 12th to the 16th centuries, Peter Lombard’s Sententiae in quatuor IV libris distinctae was the most influential theological text in Christendom. Indeed, no other piece of Christian literature save Scripture has garnered more commentaries: some fourteen hundred are extant. The last major theologian to comment on the Book of Sentences was the young Martin Luther, preceded by every prominent theological figure of the previous four hundred years, such as Alexander of Hales, Bonaventure, Thomas Aquinas, Duns Scotus, Ockham, Peter of Auriol, Marsilius of Inghen, and Gabriel Biel:”(For an excellent introduction to Lombard and his work, see Philipp W. Rosemann, Peter Lombard [OUP, 2004], esp. pp. 205-206 on how Aquinas consciously departed from Lombard stylistically: “We know from Tolomeo of Lucca that, in 1265-1267, Aquinas undertook a second, now lost, redaction of the first book of his Sentences commentary. Yet after book 1 he gave up, presumably because the structure of the Book of Sentences did not enable him to articulate his own vision of systematic theology. Subsequently, Thomas embarked on the composition of the Summa theologiae, which allowed him to create a new order for his theological material.”)”:. And the Sentences was not only a seminal theological text: much of the cutting-edge discussion and debate over optics and motion in the early fourteenth century took place in Sentences commentaries:”(See the thinkers and sources discussed in Katherine Tachau, Vision and Certitude in the Age of Ockham [Leiden: E.J. Brill, 1988])”:. With this introductory comment on Lombard, here are Fr. Michael Buckley’s comments on the fateful decision to substitute Aquinas for Lombard as the standard textbook theology in Europe:
“In 1526, at the University of Salamanca, the first theologian, Francisco de Vitoria, introduced an unprecedented procedure into the teaching of systematic theology in Spain. Following his former teacher, Peter Crockaert, he commented not on the Book of Sentences of Peter Lombard, but on the Summa Theologia of Thomas Aquinas. Stealing into the great universities beyond the Pyrenees was the spring of the “Second Thomism.” Lombard had held medieval theology together, presenting a common series of texts upon which vastly different theological structures could be built. The Sentences gave all the theologians of the Middle Ages, irrespective of the color of their convictions, a common language and a common tradition within which the conflicting theologies of Duns Scotus, William of Ockham, Durandus of St. Purcain, and Thomas Aquinas could contact and speak intelligibly with one another. The Sentences provided for the Middle Ages what Catholic theology has never been able to regain: a focus or a unity precisely within dispersion, a common series of theological statements, a vocabulary and a common intellectual tradition which allowed substantial disagreements, and an irreducible pluralism within a shared culture. Vitoria’s decision to split from this common language and tradition, opting for the work of Aquinas over the Lombard’s ordered assemblage of texts from the Fathers of the Church which were the common possession of all Christians. This factional schism within Catholic theology paralleled the sectarian divisions which were increasingly polarizing Christianity [i.e., the Reformation]. The Jesuits of the Roman College followed Salamanca’s suit, and [Leonard] Lessius in his turn brought the Summa Theologia of Aquinas into the Netherlands as the primary theological text. The University of Louvain first opposed and then adopted this innovation.”
—-Michael J. Buckley, S.J., The Origins of Modern Atheism[Cambridge,Mass:Yale Univ. Press, 1990] 43.