The Speculum maius (first manuscript completed by 1244) is recognized as the greatest encyclopedia before the eighteenth century French Encydopedie. The compiler of this encyclopedia, Vincent of Beauvais (1190?-1264), collected and presented all the knowledge available to the thirteenth century Latin West. The Speculum maius, therefore, offers an insight into the thought of the thirteenth century, the formative period of the High Middle Ages. It also provides ideal material with which to examine the elusive notion of authority (auctoritas). In the introduction, 'Apologia Actoris', Vincent defines and classifies the different kinds of authority he used in the Speculum maius. This paper explicates Vincent's idea of epistemological authority and considers some of the wider historical implications of his idea. In chapter 12 of Apologia Actoris, Vincent maps out a hierarchical structure of authority. The ultimate authority is Holy Scripture, which is beyond any debate or any authority of the Church. Next to Holy Scripture, Vincent says he wants (volui) to give the same, highest degree of authority to the canonized Saints and the papal bulls and conciliar cannons. He further explains the relationship between these two categories in a somewhat enigmatic sentence : "Therefore, both kinds are appropriately placed in the first degree of authority, because as the exceeding and the exceeded they are mutually given precedence to each other (Utrumque ergo genus in primo auctoritatis gradu merito ponitur, quoniam ut excedentia et excessa sibi vicissim preferuntur)." The middle rank of authority is given to Christian scholars who were prudent and catholic, but not canonized. The lowest rank of authority is given to non-Christian scholars and philosophers ; despite their ignorance of the truth of catholic faith, they made statements that may well be proven true by catholic faith and human reason. Vincent denies any authority to apocryphal texts on the grounds that they are either written anonymously or of dubious verity. In describing the first rank of authority, Vincent shows a certain tentativeness which he does not display when dealing with other ranks of authority. Vincent places the authority of Saints and that of papal bulls and conciliar cannons at the same level. In other words, he places inner authority at the same level as the social authority of the Church. He further states these two to be of a mutually supplementing nature. As opposed to when he describes other ranks of authority, he does not present this view as a given norm. He wants to recognize them as of the same dignity; this is his personal opinion. In order to understand this peculiar mode of presentation, we need to take into consideration the person of Vincent and the social situation of his time. Vincent was a Dominican. Dominicans combined preaching and contemplation. Vincent was also a close associate and even lector of the Cistercians. He shared their criticism of the state of the world (including the institutional Church) and shared their strong inclination toward contemplation. Vincent was convinced of the efficacy of inner authority. In this temporal world, the ultimate way to the truth of God seemed to be the experience of personal communion with God, the experience toward which contemplation strives. Vincent trusted the Church to shepard believers. However, Vincent also believed that in some cases the inner authority of exceptional individuals could supersede the social authority of the Church. This is so because these individuals have direct knowledge of transcendental reality attained through personal communion with God. But Vincent knew that such a view could be accused of heresy by those who held the social authority of the Church firmly above the inner authority of individual believers. Since the late twelfth century, the proliferation of heresy was a most pressing problem for the Church. One of the crucial points in defining heresy was balancing the authority of individual believers with that of the Church. The dichotomy of inner and social authority is already manifest in the Gospels. Nevertheless, though never denied, inner authority was never given a clear position in the structure of Church. Vincent, therefore, had to be tentative in his assertion of the value of inner authority. Further evidence that Vincent valued inner authority can be seen in his statements that he compiled the encyclopedia as a guide, and that readers should make their own judgments. Evidence is also found in the way he cites the authors' names for his quotations in the main texts, not in the margin, lest they should be lost or become obscure through the mistakes of scribes. Vincent's emphasis on inner authority has wider historical implications. For one, the question of balance between inner and social authority, which re-surfaced during the Reformation era, has not been solved even today. It also draws attention to the question of European individualism, particularly to the view that it had its germination in the Middle Ages (cf. among others, Jan A. Aertsen and Andreas Speer eds, Individuum und Individualitdt im Mittelalter (Berlin/New York, 1996); Aaron Gurevich, The Origins of European Individualism Oxford/Cambridge, Mass., 1995; Colin Morris, The Discovery of the Individual 1050-1200 Tronto, 1972).