Mark also what follows. "We may perceive," says he, "the same thing to be true of hearing, smelling, and seeing, -- that to hear, and to smell, and to see is of our own power, while the ability to hear, and to smell, and to see is not of our own power, but lies in a natural necessity." Either I do not understand what he means, or he does not himself. For how is the possibility of seeing not in our own power, if the necessity of not seeing is in our own power because blindness is in our own power, by which we can deprive ourselves, if we will, of this very ability to see? How, moreover, is it in our own power to see whenever we will, when, without any loss whatever to our natural structure of body in the organ of sight, we are unable, even though we wish, to see, -- either by the removal of all external lights during the night, or by our being shut up in some dark place? Likewise, if our ability or our inability to hear is not in our own power, but lies in the necessity of nature, whereas our actual hearing or not hearing is of our own will, how comes it that he is inattentive to the fact that there are so many things which we hear against our will, which penetrate our sense even when our ears are stopped, as the creaking of a saw near to us, or the grunt of a pig? Although the said stopping of our ears shows plainly enough that it does not lie within our own power not to hear so long as our ears are open; perhaps, too, such a stopping of our ears as shall deprive us of the entire sense in question proves that even the ability not to hear lies within our own power. As to his remarks, again, concerning our sense of smell, does he not display no little carelessness when he says "that it is not in our own power to be able or to be unable to smell, but that it is in our own power" -- that is to say, in our free will -- "to smell or not to smell?" For let us suppose some one to place us, with our hands firmly tied, but yet without any injury to our olfactory members, among some bad and noxious smells; in such a case we altogether lose the power, however strong may be our wish, not to smell, because every time we are obliged to draw breath we also inhale the smell which we do not wish.