Chatton’s appeal to the Eucharist, where a piece of bread miraculously converts into the substance of the body of Christ, is unsurprising in the late medieval context though striking to modern eyes. Transubstantiation forced medieval theologians, trained in Aristotle’s metaphysics and natural philosophy, to think about a number of philosophical issues including the inherence (or non-inherence) of accidents in their substances but also the ontological status of quantity. Prior to consecration, the host is a piece of bread whose substance is bread substance and has various perceptible accidental qualities and quantities, e.g. being-white, being-round, having such and such dimensions, etc. During consecration, when the bread substance has been converted into the substance of the body of Christ, all the bread’s perceptible accidents remain present yet without being anchored in the bread substance.