"Action implies motion; but there may be motion, as in a clock, where, properly speaking, there is no agent. Many motions necessary to life are continually going on in the human body; as those of the heart, lungs, and arteries: but these are not human actions, because man is not the cause of them. For the same reason, breathing, and the motion of the eyelids, are not actions; because, though we may act for a little time in suspending them, for the purpose of seeing or hearing more accurately, they commonly go on without any care of ours; and, while they do so, we are, in regard to them, not active, but passive. ... All action is the work of an agent, that is, of a being who acts; and every being who acts is the beginner of that motion which constitutes the action."