“We do not know what it's like to be a bat, we do not know what it's like to be in coma. we can't even say that we know what it's like to be sleeping. We can say what it's like to be restored to consciousness after sleeping. If there are no dreams during our sleep then the sleeping life is an empty life. We might say of such a life that it's not like being anything. We protect that life on the assumption that come the morning its normal functions will be restored. Suppose it was the case however that such functions were only restored every two days... every eight days... twice a year but only briefly. I assume the point is clear. Actions that end life are irretrievable. If we are mistaken at that point there is no going back.”