"Let us not believe that that external fast from visible food alone can possibly be sufficient for perfection of heart and purity of body unless with it there has also been united a fast of the soul. For the soul also has its foods which are harmful, fattened on which, even without superfluity of meats, it is involved in a downfall of wantonness. Slander is its food, and indeed one that is very dear to it. A burst of anger also is its food, even if it be a very slight one; yet supplying it with miserable food for an hour, and destroying it as well with its deadly savour. Envy is a food of the mind, corrupting it with its poisonous juices and never ceasing to make it wretched and miserable at the prosperity and success of another. Kenodoxia, i.e., vainglory is its food, which gratifies it with a delicious meal for a time; but afterwards strips it clear and bare of all virtue, and dismisses it barren and void of all spiritual fruit, so that it makes it not only lose the rewards of huge labours, but also makes it incur heavier punishments. All lust and shifty wanderings of heart are a sort of food for the soul, nourishing it on harmful meats, but leaving it afterwards without share of the heavenly bread and of really solid food. If then, with all the powers we have, we abstain from these in a most holy fast, our observance of the bodily fast will be both useful and profitable. For labour of the flesh, when joined with contrition of the spirit, will produce a sacrifice that is most acceptable to God, and a worthy shrine of holiness in the pure and undefiled inmost chambers of the heart."