I argue that Plato thinks that a is a mere tool used by a soul (or by the cosmic ) to promote an intended outcome. In the first section, I develop the connection between and Plato’s teleology. In the second section, I argue that belong to Plato’s theory of the soul as a self-mover: specifically, they are those things that are set in motion by the soul in the service of some goal. I also argue against several popular and long-standing interpretations, namely, that correspond to Aristotle’s idea of hypothetical necessity, that are the ‘ ’ in an explanation (whereas the true cause is the ‘ ’), and that Plato’s causal views should be read through Aristotle’s fourfold schema. I conclude the article by surveying the history of after Plato’s usage.