91 Why do you seek for a heap of riches as though it were necessary? Nothing is so necessary as to know that this is not necessary. Why do you throw the blame on the flesh? It is not the belly in the body but avarice in the mind which makes a man insatiable. Does the flesh take away the hope of the future? Does the flesh destroy the sweetness of spiritual grace? Does the flesh hinder faith? Is it the flesh which attributes any weight to vain opinions as it were to insane masters? The flesh prefers frugal moderation, by which it is freed from burdens, is clothed with health, because it has laid aside its care and has obtained tranquillity.
Source: Letters (New Advent)