 The will is one of three appetitive powers within us, distinguished from the irascible and concupiscible powers in being not a sensual appetite, the source of the passions (King 1998; Miner 2009), but a rational appetite, the source of voluntary agency. Its rationality consists in the way it is coordinate with intellect, taking as its inputs the intellect’s practical judgments regarding what is to be done. Since the will’s function is strictly appetitive, it cannot render its own practical judgments, and to that extent can act only on the basis of intellect: “every choice and actual will within us is immediately caused by an intelligible apprehension” (SCG III.85.3). But that is by no means to say that the will is determined by the intellect’s judgment, because ultimately our will has the power to control what we think about: “the will moves both itself and all other capacities. For I think when I want to, and likewise I use all my other capacities and dispositions because I want to” (Quest. on Evil 6c). To be sure, by its very nature, the will can desire only what is presented to it as a good (ST 1a2ae 8.1). Accordingly, since our ultimate happiness (beatitudo) is good in every respect, “human beings have an appetite of necessity for happiness” (ST 1a2ae 10.2c; see §8.1). But, with regard to any specific course of action, there are always multiple perspectives from which the situation can be judged, and the will can control how we think about things—whether, for instance, we decide to focus on how rewarding a thing would be or on how tiring it would be. Even in the case of our ultimate happiness, moreover, the will can choose not to think about it, and so even in that extreme case the will’s choices are not necessitated. On this basis Aquinas adamantly insists on human freedom of choice, and treats claims that the will is necessitated as “contrary to the faith and subverting all of the principles of moral philosophy” (Quest. on Evil 6c).