For a man that sits still is said yet to be at liberty; because he can walk if he wills it.

A man that walks is at liberty also, not because he walks or moves; but because he can stand still if he wills it.

But if a man sitting still has not a power to remove himself, he is not at liberty; so likewise a man falling down a precipice, though in motion, is not at liberty, because he cannot stop that motion if he would.

This being so, it is plain that a man that is walking, to whom it is proposed to give off walking, is not at liberty, whether he will determine himself to walk, or give off walking or not: he must necessarily prefer one or the other of them; walking or not walking.

And so it is in regard of all other actions in our power they being once proposed, the mind has not a power to act or not to act, wherein consists liberty.