In this mass of theological writings one book stands out as the contribution which for three centuries most influenced university instruction in theology. This is the "Sentences" _(Sententiae)_ of Peter Lombard (c. 1100-1160), in four books. The subjects discussed in this work are similar to those treated by Abelard in the _Sic et Non_ (see p. 20). In not a few instances it adopts the form of presentation used in that book, i.e., the citation of authorities on both sides of the case. Like the _Decretum_ of Gratian, it is an illustration of the widespread influence of the _Sic et Non._ A great number of commentaries were written upon this book. A manuscript note in one of the copies in the Harvard library states that four hundred and sixty such commentaries are known; but I have been unable to verify the statement. In theory, the Bible was studied in the Faculties of Theology in addition to the "Sentences"; but in the thirteenth century and later it seems to have occupied, in practice, a minor share of the student's attention. To this effect is the criticism of Roger Bacon in 1292: Although the principal study of the theologian ought to be in the text of Scripture, as I have proved in the former part of this work, yet in the last fifty years theologians have been principally occupied with questions [for debate] as all know, in tractates and summae,--horse-loads, composed by many,--and not at all with the most holy text of God. And accordingly, theologians give a readier reception to a treatise of scholastic questions than they will do to one about the text of Scripture.... The greater part of these questions introduced into theology, with all the modes of disputation (see p. 115) and solution, are in the terms of philosophy, as is known to all theologians, who have been well exercised in philosophy before proceeding to theology. Again, other questions which are in use among theologians, though in terms of theology, viz., of the Trinity, of the fall, of the incarnation, of sin, of virtue, of the sacraments, etc., are mainly ventilated by authorities, arguments, and solutions drawn from philosophy. And therefore the entire occupation of theologians now-a-days is philosophical, both in substance and method.[33] (e) _Medicine_