Aquinas’s Commentary on Aristotle’s Ethics 1.1.6-14
Moral philosophy, or the science of human action, has three principal branches: individual or “monastic” ethics, which studies individual action; domestic ethics, which studies the actions of the household; and political science or politics, which studies the actions of the political community (§6). Some of the first “principles” or sources of human action studied under the science of individual ethics are the human powers of reason and will, by which human beings are able to apprehend theoretical and practical truths and to make choices and then act on those choices (§8). The proper object of the will, moving the individual to action, is some intellectually apprehended good, where the good is understood as that property of things insofar as they are an object of desire (§9). Even when men desire evil, they desire it not as evil, but as somethinggood and hence desirable by the will, but which happensto be evil or defective in good (§10). This desire for and pursuit of the good, however, is not in fact limited to human beings, but is true of non-rational things as well, which have been impressed with a natural tendency towards their good by the divine reason (§11). Thus it is true not just of human beings but of all things that they desire and seek the good, though the goods that they seek differ according to their nature. What all goods have in common, however, is a certain likeness to and participation in the highest good which is God, such that the desire for any particular good is, after a fashion, a desire for God.
The goods or ends that things desire may be further divided into two subcategories: the end of a thing’s operation or activity itself, and the end that is the object achieved by the operation or activity (§12). Corresponding to these two categories of ends is a distinction between human activities themselves: one type of action (sometimes called “immanent”) remains wholly within the actor himself, such as the acts of desiring or thinking; the other type of action (sometimes called “transitive”) has its terminus outside of the agent and in an external object, and which is called “making” (§13). Among transitive actions, however, Aquinas further distinguishes between a person merely using an external good, such as a horse for riding or a music instrument for playing, and a person transforming external matter, as when a carpenter builds a house or a bed. What immanent actions of thinking and willing have common, accordingly, with transitive actions of mere use is that neither of them result in a new product, but in each case the activity itself is the end, though Aquinas views immanent actions as the “more excellent” of the two because they remain wholly within the actor himself. When the point of an action is to produce an external object, however, in this case it is the external object that is to be deemed as more important than the action that produced it (§14).
The Natural Law Libertarian 