An unresolved question in sacramental theology is whether the Mass is to be considered as limited or unlimited in its efficacy, and in what sense. In modern times, this question has been less discussed, in part from a concern that it is incorrect to attempt to speak of spiritual realities in quantitative terms. I defend the use of such quantitative language, and its application to the so-called special fruit of the Mass, understood both ‘intensively’ and ‘extensively’. I then summarise the two principal positions taken on the question of the efficacy of the Mass, referring to an important representative of each, Cajetan and Bellarmine. I argue that neither position is fully satisfying. I note that authors have generally failed to find a coherent position in Aquinas's two treatments of the question. I argue that these two positions are in fact coherent, and when combined allow for a new proposal about the fruits of the Mass, integrating the insights of all parties. This proposal may be summed up as intensive infinitude and extensive finitude. I finish by an analogy between the Mass thus understood and one aspect of Aquinas's Christology.