 (3) Aristotle argues for the priority in substance of actuality over potentiality in two ways. (a) The first argument makes use of his notion of final causality. Things that come to be move toward an end (telos)—the boy becomes a man, the acorn becomes an oak—and “the activity is the end, and it is for the sake of this that the capacity [or potentiality] is acquired. For animals do not see in order that they may have sight, rather they have sight in order that they may see … matter is potentially something because it may come in the form of it—at any rate, when it is actively something, then it is in the form of it” (1050a9–17). Form or actuality is the end toward which natural processes are directed. Actuality is therefore a cause in more than one sense of a thing’s realizing its potential. As we noted in Section 11, one and the same thing may be the final, formal, and efficient cause of another. Suppose an acorn realizes its potential to become an oak tree. The efficient cause here is the actual oak tree that produced the acorn; the formal cause is the logos defining that actuality; the final cause is the telos toward which the acorn develops—an actual (mature) oak tree.