Principle

Aristotle calls a principle that from which someone first moves something. Or it could be that by which something best comes into being. The starting point of instruction. An example of a principle would be the keel of a ship or the foundation of the house. Though there is disagreement whether the the principle in animals would be the heart or the brain.

It is that non-inherent first thing, from which, something comes into being.

The term 'principle' implies an order in sequence. It is what is first in any order.