  Nature, according to Aristotle, is an inner principle of change and being at rest (Physics 2.1, 192b20–23). This means that when an entity moves or is at rest according to its nature reference to its nature may serve as an explanation of the event. We have to describe how—to what extent, through what other processes, and due to what agency—the preconditions for the process of change or of being at rest are present, but once we have provided an account of these preconditions, we have given a complete account of the process.  The nature of the entity is in and of itself sufficient to induce and to explain the process once the relevant circumstances do not preempt it.