Aims, principles, &c., have a place in our thoughts, in our subjective design only; but not yet in the sphere of reality. That which exists for itself only, is a possibility, a potentiality; but has not yet emerged into Existence. A second element must be introduced in order to produce actuality — viz. actuation, realization; and whose motive power is the Will — the activity of man in the widest sense.

Lectures on the Philosophy of History Vol 1 of 3 (1832)