ABSTRACT
When we consider will (or practical reason), we may define it as a kind of causality (a power of causal action) belonging to living beings so far as they are rational. To describe such a will as free would be to say that it can act causally without being caused to do so by something other than itself. Non-rational beings can act causally only so far as they are caused to do so by something other than themselves, and this is what is meant by natural necessity as opposed to freedom: if one billiard ball causes another to move, it does so only because it has itself been caused to move by something else.
