if another take your hand and with it strike a third person, that is not a voluntary act of yours, for it was not within your control; again the man you strike may be your father, and you may know that it is a man, or perhaps that it is one of the company, that you are striking but not know that it is your father; and it must be understood that the same distinction is to be made with regard to the result, and, in a word, to the whole act. That then which either is done in ignorance, or, though not done in ignorance, is not under our control, or is done under compulsion, is involuntary; besides which, there are many natural processes in which we knowingly take an active or a passive part, which cannot be called either voluntary or involuntary, such as growing old and dying.