 If basic theological premises require revelation for human beings to know them, then the arena of human reason in theology is restricted to reasoning about what is revealed. Some of the tenets of Christian doctrine, like the doctrines of the Trinity, Incarnation and Eucharist, offer particular challenges to logic. There was a general belief among medieval scholastics that Aristotelian logic exemplified natural reason at its best and was universally applicable to all domains because its rules held through formal relation to the principle of non-contradiction. If key Christian doctrines were not amenable to Aristotelian logical principles, however, it would seem to imply that God is not subject to the principle of non-contradiction and that Aristotelian logic is not universal. Holkot took up these issues in his discussion of the doctrine of the Trinity.