DAVID of Dinant (DINAN). - A medieval philosopher about whose life and activities we have scant information. Born in Dinant in the province of Liège, or according to others in Brittany, in a document of 1206 he is called by Innocent III "our master and chaplain" (PL 225, 901-902). In 1210 a provincial council of Paris condemned his doctrine together with that of Amaury of Bène, ordering that anyone possessing his writings (quaternuli) should surrender them under pain of excommunication to be consigned to the flames (H. Denifle-A. Chatelain, *Chartularium Universitatis Parisiensis*, I, Paris 1889, p. 70). In 1215 Robert de Courçon, in a letter addressed to the University of Paris, repeated the condemnation: "The books of Aristotle on metaphysics and natural philosophy should not be read, nor the compendia of these works or the doctrine of D. of D." (ibid., p. 79). The decrees were so rigorously enforced that none of D.'s writings have come down to us. The condemnation decree itself and various passages from 13th-century philosophers reveal the main lines of his system. Albert the Great reports having known a collection of propositions by D. (*Summa de creaturis*, part 2, q. 5, a. 2), probably extracted from his works on the occasion of the synod.
Albert the Great devoted three discussions to the system of the master of Dinant: *Summa de creaturis* (part 2, q. 5, a. 2) and *Summa theologica* (part 2, tr. I, q. 4, quæst. incid. 2, m. 3; tr. XII, q. 72, m. 4, a. 2), and cites verbatim the work before him, of which he also reports the title *Liber de tomis, sive de divisionibus*. Fr. G. Théry believes with good reason that this writing should be identified with the *quaternuli* condemned by the Council of Paris, and, using the extracts preserved by Albert the Great and St. Thomas, offers a reconstruction from which some corollaries can be easily deduced that shed sufficient light on the teaching of Master D. He was certainly a materialist, and St. Thomas precisely identifies this character of his system.
"It was an error," says the Aquinate, "of some ancient philosophers to believe that God entered as an essential element into all things. They held that all realities were one and did not differ from one another, as Parmenides said, according to sense and opinion. These ancient doctrines were adopted by some moderns, among whom was D. of Dinant." D. groups substances into three categories: that of bodies, that of souls, and that of separate and eternal substances; he denies any distinction among them and affirms that they form a single and identical reality, a single essence. However, D. is not a materialist in the modern sense of the word, because alongside matter he posits a second principle of existence.
In the world of bodies, according to his doctrine, the only indivisible reality is prime matter, in which the many beings of the physical world are identified, but in the sphere of human spirits and separate substances the same role is played by the intellect and by God. But an identical reality must be posited between God, the intellect, and matter, and consequently a single substance is to be considered as existing, not only of all bodies but also of all souls: and this is nothing other than God. And since the substance from which bodies derive is called *hyle*, and that from which souls derive is called *ratio* or *mens*, it must be deduced that God is the reason of all souls and of all bodies. This is the conclusion of Albert the Great's critique of the teaching of D. of D. in the cited passages of the *Summa de creaturis* and the *Summa theologica*.
Among the ancient philosophers who most influenced D. of D. Aristotle must be placed. Indeed, all the philosophy of D. of D. is based on Aristotelianism. He argues about act and potency, substance and accident, the distinction of causes: his system appears devised with the aim of preserving the double principle of matter and form of Aristotle. And he arrives at the theory of the unity of being, keystone of his doctrinal edifice, by having misunderstood certain fundamental tenets of the great master's thought. At the end of the 12th century he was one of the representatives of the philosophical movement that introduced into Christian Europe the Aristotelianism that had passed through Arabic philosophy. This was the reason that drew upon him the attention and condemnation of his contemporaries.