ABSTRACT
The most characteristic academic exercise in the medieval university was the disputation. A student needed to display skill at formal disputation in order to graduate at any level, or degree, whether the bachelor's, master's, or doctor's; consequently, developing such skill by participating in disputations was a regular part of university life. Both God and nature act against individual nature: for instance, it is against the nature of this or that particular fire that it be extinguished. Although God can do something contrary to the relation between one creature and another, he cannot do anything contrary to a creature's relation to himself. Just as God can produce effects in nature without employing natural causes, so also can he without the ministry of the angels. Just as God cannot make yes and no to be true at the same time, so neither can he do what is impossible in nature in so far as it includes the former impossibility.
