What analogy does Aquinas use to illustrate teleological purpose in nature?

Aquinas uses the analogy of the bow and the arrow to illustrate teleological purpose in nature effectively. In this analogy, the bow represents an agent or cause that is directed toward achieving an end—represented by the arrow. The arrow, once shot from the bow, is aimed at a target, demonstrating the idea that all things in nature have a purpose or goal they are directed toward. This reflects Aquinas's belief that natural objects and processes exhibit intentionality and function in a way that is aligned with a predetermined goal, which is a fundamental aspect of teleological thinking.

Teleology essentially concerns itself with the ends or purposes of things, and Aquinas argues that just as an arrow does not move towards a target by itself but requires the bow (its cause) to direct it, so too do natural entities require an ultimate purpose or final cause. The arrows are not merely objects; they achieve their purpose only when utilized correctly, just as natural beings realize their full potential in accordance with their intended purposes. Hence, this analogy effectively captures the essence of teleological explanation in Aquinas’s philosophy.