From Seneca:
I will not relinquish old age if it leaves my better part intact. But if it begins to shake my mind, if it destroys its faculties one by one, if it leaves not life but breath, I will depart from the putrid and tottering edifice. I will not escape death so long as it may be healed, and leaves my mind unimpaired. I will not raise my hand against myself on account of pain, for so to die is to be conquered. But I know that if I must suffer without hope of relief, I will depart, not through fear of the pain itself, but because it prevents all for which I would live.
Fourteen Twenty 