Our Lord's Sermon on the Mount

⁴⁴ Rightly, therefore, does he who is intent on cleansing our heart follow up what He has said with a precept, where He says: “Lay not up for yourselves treasures upon earth, where moth and rust does corrupt, and where thieves break through and steal: but lay up for yourselves treasures in heaven, where neither moth nor rust does corrupt, and where thieves do not break through nor steal. For where your treasure is, there will your heart be also.” If, therefore, the heart be on earth, i.e. if one perform anything with a heart bent on obtaining earthly advantage, how will that heart be clean which wallows on earth? But if it be in heaven, it will be clean, because whatever things are heavenly are clean. For anything becomes polluted when it is mixed with a nature that is inferior, although not polluted of its kind; for gold is polluted even by pure silver, if it be mixed with it: so also our mind becomes polluted by the desire after earthly things, although the earth itself be pure of its kind and order. But we would not understand heaven in this passage as anything corporeal, because everything corporeal is to be reckoned as earth. For he who lays up treasure for himself in heaven ought to despise the whole world. Hence it is in that heaven of which it is said, The heaven of heavens is the Lord's, i.e. in the spiritual firmament: for it is not in that which is to pass away that we ought to fix and place our treasure and our heart, but in that which ever abides; but heaven and earth shall pass away.

45. And here He makes it manifest that He gives all these precepts with a view to the cleansing of the heart, when He says: “The candle of the body is the eye: if therefore your eye be single, your whole body shall be full of light. But if your eye be evil, your whole body shall be full of darkness. If, therefore, the light [lamp] that is in you be darkness, how great is that darkness!” And this passage we are to understand in such a way as to learn from it that all our works are pure and well-pleasing in the sight of God, when they are done with a single heart, i.e. with a heavenly intent, having that end of love in view; for love is also the fulfilling of the law. Hence we ought to take the eye here in the sense of the intent itself, wherewith we do whatever we are doing; and if this be pure and right, and looking at that which ought to be looked at, all our works which we perform in accordance therewith are necessarily good. And all those works He has called the whole body; for the apostle also speaks of certain works of which he disapproves as our members, and teaches that they are to be mortified, saying, “Mortify therefore your members which are upon the earth; fornication, uncleanness, covetousness,” and all other such things.

46. It is not, therefore, what one does, but the intent with which he does it, that is to be considered. For this is the light in us, because it is a thing manifest to ourselves that we do with a good intent what we are doing; for everything which is made manifest is light. For the deeds themselves which go forth from us to human society, have an uncertain issue; and therefore He has called them darkness. For I do not know, when I present money to a poor man who asks it, either what he is to do with it, or what he is to suffer from it; and it may happen that he does some evil with it, or suffers some evil on account of it, a thing I did not wish to happen when I gave it to him, nor would I have given it with such an intention. If, therefore, I did it with a good intention,— a thing which was known to me when I was doing it, and is therefore called light—my deed also is lighted up, whatever issue it shall have; but that issue, inasmuch as it is uncertain and unknown, is called darkness. But if I have done it with a bad intent, the light itself even is darkness. For it is spoken of as light, because every one knows with what intent he acts, even when he acts with a bad intent; but the light itself is darkness, because the aim is not directed singly to things above, but is turned downwards to things beneath, and makes, as it were, a shadow by means of a double heart. “If, therefore, the light that is in you be darkness, how great is that darkness!” i.e., if the very intent of the heart with which you do what you are doing (which is known to you) is polluted by the hunger after earthly and temporal things, and blinded, how much more is the deed itself, whose issue is uncertain, polluted and full of darkness! Because, although what you do with an intent which is neither upright nor pure, may turn out for some one's good, it is the way in which you have done it, not how it has turned out for him, that is reckoned to you.