The work of the heart binds the external members. And it is evident whether a man does the work of the heart with discernment, following the example of the Fathers who have gone before us, if in the presence of external things he is not tied by material profit, despises gluttony, and is entirely free of anger. But if these three are found in a man, namely, the desire for material gain (whether to a greater or lesser degree), quick temper, and submission to gluttony, then, even though he seem to be a peer of the saints of old, know that his laxity in externals is produced by his lack of patience in inward matters; these things, however, are not produced by a discriminating disdain of one’s soul. If this were not so, how could he have despised bodily things and still not have acquired meekness? Discriminating disdain is accompanied by non-attachment, scorn of ease and the love of mankind. If a man readily and joyfully accepts a loss for the sake of God is he inwardly pure. And if he does not look down upon any man because of his defects, in very truth he is free. If a man is not pleased with someone who honours him, nor displeased with someone who dishonours him, he is dead to the world and to this life. The watchfulness of discernment is superior to every kind of discipline accomplished by men of any degree.
The Ascetical Homilies of Saint Isaac the Syrian, I, 51, translated by the Holy Transfiguration Monastery, Boston, 1984. 250.