The Work
Peter Lombard's Sententiarum libri quatuor (Four Books of Sentences) was completed around 1150 and dedicated to Pope Alexander III. It is organized into four books: Book I treats God and the Trinity; Book II treats creation, angels, the fall, and sin; Book III treats the Incarnation, virtues, and commandments; Book IV treats the sacraments and the last things. Each section presents a question, assembles relevant quotations from Scripture and the Church Fathers (Augustine being the most frequently cited), and offers a tentative resolution of apparent contradictions.
The work's genius lay not in its originality but in its organization. Lombard had access to a vast patristic tradition and to the dialectical methods being developed in the Paris schools, and he deployed both to create a comprehensive, teachable summary of Christian doctrine. The format - the sic et non (yes and no) structure of assembled authorities - was pioneered by Abelard but given systematic theological shape by Lombard. By the thirteenth century, the Sentences had displaced all other texts as the standard theological textbook at Paris and all European universities. Every candidate for the Bachelor of Sacred Theology was required to lecture on the Sentences, and producing a commentary on Lombard became the essential rite of passage for medieval theologians.
Biblical Engagement
The Sentences is essentially an organized commentary on Scripture as refracted through the patristic tradition. Genesis 1:1 and the creation account anchor Book II's discussion of cosmology and creation ex nihilo. John 1:1 ('In the beginning was the Word, and the Word was with God, and the Word was God') is central to Book I's Trinitarian theology, providing the scriptural basis for the distinction between the Father and the eternal Son while maintaining divine unity.
Romans 5:12 ('Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned') is the foundation of Book II's treatment of original sin and its transmission - the most contested topic in medieval theology and the one that generated the most elaborate commentary tradition, reaching its culmination in Aquinas's Summa Theologica and the Reformation debates between Luther and Erasmus.
1 Corinthians 11:24 ('This is my body, which is broken for you: this do in remembrance of me') is the central text of Book IV's treatment of the Eucharist - the sacrament that generated the most intense debate in the medieval period and in the Reformation. Lombard's relatively cautious treatment of Eucharistic presence left room for the subsequent development of transubstantiation doctrine by Aquinas while not committing to that specific formulation.
Author and Context
Peter Lombard (c. 1096-1160) was born in Novara in northern Italy (hence the Lombard of his cognomen) and educated at Rheims and Bologna before arriving in Paris, where he studied under and later succeeded Hugh of Saint-Victor. He became a canon of Notre Dame Cathedral and eventually Bishop of Paris (1159-1160), dying within months of his elevation. His academic career was spent entirely in Paris during the period when the city was becoming the intellectual capital of Western Christendom.
Lombard wrote in the context of the emerging university culture of Paris - a culture characterized by fierce dialectical debate, the recovery of Aristotelian logic, and an intense effort to reconcile the apparently conflicting authorities of Scripture and the Church Fathers. His Sentences was a product of this culture and became its primary institutional expression: the text that organized and transmitted the entire body of Latin Christian theological learning.
Influence on Theology
The Sentences commentary tradition is perhaps the most important phenomenon in the history of Western theology. Every major medieval theologian wrote a commentary: Alexander of Hales, Bonaventure, Albertus Magnus, Thomas Aquinas, John Duns Scotus, William of Ockham, Peter Auriol, and dozens of lesser figures. Aquinas's Scriptum super Sententiis (Commentary on the Sentences, c. 1253-1257) is actually his first systematic theological work, predating the Summa Theologica and showing the development of his mature thought.
The tradition did not end with the medieval period. Martin Luther wrote a commentary on the Sentences as part of his theological formation (c. 1509-1510), and his later critique of scholastic theology was in part a critique of what he saw as the deformation of Lombard's biblical theology by Aristotelian metaphysics. Melanchthon's Loci Communes (1521), the first systematic Protestant theology, was explicitly conceived as a Protestant alternative to Lombard - organized around Pauline loci (topics) rather than the four-book structure, but performing the same function of organizing and transmitting the tradition for students.
Reception
The Sentences was not without its critics. Joachim of Fiore accused Lombard of quaternity (positing four divine persons) in his treatment of the Trinity, a charge refuted at the Fourth Lateran Council (1215). Some critics found the sic et non method unsatisfying - it presented problems without always resolving them. But the book's dominance in the curriculum was so complete for four centuries that these criticisms had little practical effect.
The decline of the Sentences commentary tradition in the sixteenth century reflects the broader displacement of scholastic theology by humanist biblical scholarship. Erasmus's Greek New Testament (1516) and Luther's lectures on Romans and Galatians represented a turn away from the Sentences tradition toward direct scriptural engagement, and the Reformation made Lombard seem irredeemably associated with the Catholic doctrinal tradition that was being contested.
Legacy
The Sentences created the institutional framework within which Western theology was done for four centuries. It established systematic theology as a distinct discipline, separate from biblical commentary and patristics, and organized around the question-and-objection method that still characterizes academic theology. The four-book structure - God, creation, Incarnation, sacraments - reflects the basic architecture of the Creed and continues to influence the structure of Catholic systematic theology. The Catechism of the Catholic Church (1992), for example, follows a broadly similar organization.