The date and place of his birth are unknown. He was believed to have been the elder brother of Thierry of Chartres and to be of Breton origin, but research has shown that this is unlikely. He is recorded at the cathedral school of Chartres by 1115 and was chancellor until 1124. There is no proof that he was still alive after 1124.
Gilbert de la Porrée and William of Conches were students of his, and some information about his work comes through their writings, as well as the writings of John of Salisbury. According to John of Salisbury, Bernard composed a prose treatise De expositione Porphyrii, a metrical treatise on the same subject, a moral poem on education, and probably a fourth work in which he sought to reconcile Plato with Aristotle. Fragments of these treatises are to be found in John's Metalogicon (IV, 35) and Policraticus (VII, 3). Hauréau confounds Bernard of Chartres with Bernard Silvestris, and assigns to the former works which are to be ascribed to the latter.
Bernard of Chartres used to say that we [the Moderns] are like dwarves perched on the shoulders of giants [the Ancients], and thus we are able to see more and farther than the latter. And this is not at all because of the acuteness of our sight or the stature of our body, but because we are carried aloft and elevated by the magnitude of the giants.
Bernard, in common with others of his school, devoted more attention to the study of the Timaeus and the works of the Neo-Platonists than to the study of the dialectical treatises of Aristotle and the commentaries of Boethius. Consequently, he not only discussed the problem of universals (distinguishing between the abstract, the process, and the concrete—exemplified, for instance, by the Latin words albedo, albet, and album) but also occupied himself with problems of metaphysics and cosmology.
According to Bernard, there are three categories of reality: God, matter, and idea. God is supreme reality. Matter was brought out of nothingness by God's creative act and is the element which, in union with Ideas, constitutes the world of sensible things. Ideas are the prototypes by means of which the world was from all eternity present to the Divine Mind; they constitute the world of Providence ("in qua omnia semel et simul fecit Deus"), and are eternal but not coeternal with God. According to John of Salisbury, Bernard also taught that there exist native forms—copies of the Ideas created with matter—which are alone united with matter. It is difficult, however, to determine what was Bernard's doctrine on this point. It is sufficient to note that he reproduced in his metaphysical doctrines many of the characteristic traits of Platonism and Neo-Platonism: the intellect as the habitat of Ideas, the world-soul, eternal matter, matter as the source of imperfection, etc.
Bernard argued that matter, although caused by God, existed from all eternity. In the beginning, before its union with the Ideas, it was in a chaotic condition. It was by means of the native forms, which penetrate matter, that distinction, order, regularity, and number were introduced into the universe.
Paul Edward Dutton has shown that a set of anonymous glosses on Plato's Timaeus must be attributed to Bernard. These glosses edited by Dutton are Bernard's only extant work.