I. 4. 14
(Armstrong Selection and Translation)

[Man’s well-being is an affair of the soul, not of soul and body together (as against Aristotle): too much bodily well-being endangers the well-being of soul, and the wise man will not want it, and if he has it will seek to reduce it.]

Man, and especially the good man, is not the composite of soul and body; separation from the body and despising of its so-called goods make this plain. It is absurd to maintain that well-being extends only as far as the living body, since well-being is the good life, which is concerned with soul and is an activity of soul, and not of all of it — for it is not an activity of the growth-soul, which would bring it into connexion with body. This state of well-being is certainly not the body’s size or health, nor again does it consist in the excellence of the senses, for too much of these advantages is liable to weigh man down and bring him to their level. There must be a sort of counterpoise on the other side, towards the best, to reduce the body and make it worse, so that it may be made clear that the real man is other than his outward parts. The man who belongs to this world may be handsome and tall and rich and the ruler of all mankind (since he is essentially of this region), and we ought not to envy him since he is cheated by things like these. The wise man will perhaps not have them at all, and if he has them will himself reduce them, if he cares for his true self. He will reduce and gradually extinguish his bodily advantages by neglect, and will put away authority and office. He will take care of his bodily health, but will not wish to be altogether without experience of illness, and still less of pain. If these do not come to him when he is young he will want to learn them, but when he is old he will not want either pains or pleasures to hinder him, or any earthly thing, pleasant or the reverse, so that he may not have to consider the body. When he finds himself in pain he will oppose to it the power which he has been given for the purpose; he will find no help to his well-being in pleasure and health and freedom from pain and trouble, nor will their opposites take it away or diminish it. For if one thing adds nothing to a state, how can its opposite take anything away?