1 Corinthians 11:1
5 And although what has been said is sufficient to convince you that no otherwise is it possible to secure our own benefit: yet if you would also assure yourself of it by the examples of common life, conceive a fire happening any where to be kindled in a house, and then some of the neighbors with a view to their own interest refusing to confront the danger but shutting themselves up and remaining at home, in fear lest some one find his way in and purloin some part of the household goods; how great punishment will they endure? Since the fire will come on and burn down likewise all that is theirs; and because they looked not to the profit of their neighbor, they lose even their own besides. For so God, willing to bind us all to each other, has imposed upon things such a necessity, that in the profit of one neighbor that of the other is bound up; and the whole world is thus constituted. And therefore in a vessel too, if a storm come on, and the steersman, leaving the profit of the many, should seek his own only, he will quickly sink both himself and them. And of each several art too we may say that should it look to its own profit only, life could never stand, nor even the art itself which so seeks its own. Therefore the husbandman sows not so much grain only as is sufficient for himself, since he would long ago have famished both himself and others; but seeks the profit of the many: and the soldier takes the field against dangers, not that he may save himself, but that he may also place his cities in security: and the merchant brings not home so much as may be sufficient for himself alone, but for many others also.
Now if any say, “each man does this, not looking to my interest, but his own, for he engages in all these things to obtain for himself money and glory and security, so that in seeking my profit he seeks his own:” this also do I say and long since wished to hear from you, and for this have I framed all my discourse; viz. to signify that your neighbor then seeks his own profit, when he looks to yours. For since men would no otherwise make up their mind to seek the things of their neighbor, except they were reduced to this necessity; therefore God has thus joined things together, and suffers them not to arrive at their own profit except they first travel through the profit of others.
Well then, this is natural to man, thus to follow after his neighbors' advantage; but one ought to be persuaded not from this reason, but from what pleases God. For it is not possible to be saved, wanting this; but though you should exercise the highest perfection of the work and neglect others who are perishing, you will gain no confidence towards God. Whence is this evident? From what the blessed Paul declared. “For if I bestow my goods to feed the poor, and give my body to be burned, and have not love, it profits me nothing,” says he. Sees thou how much Paul requires of us? And yet he that bestowed his goods to feed the poor, sought not his own good, but that of his neighbor. But this alone is not enough, he says. For he would have it done with sincerity and much sympathy. For therefore also God made it a law that he might bring us into the bond of love. When therefore He demands so large a measure, and we do not render even that which is less, of what indulgence shall we be worthy?
“And how,” says one, “did God say to Lot by the Angels, 'Escape for your life?'” Say, when, and why. When the punishment was brought near, not when there was an opportunity of correction but when they were condemned and incurably diseased, and old and young had rushed into the same passions, and henceforth they must needs be burned up, and in that day when the thunderbolts were about to be launched. And besides, this was not spoken of vice and virtue but of the chastisement inflicted by God. For what was he to do, tell me? Sit still and await the punishment, and without at all profiting them, be burned up? Nay, this were the extremest folly.
For I do not affirm this, that one ought to bring chastisement on one's self without discrimination and at random, apart from the will of God. But when a man tarries long in sin, then I bid you push yourself forward and correct him: if you will, for your neighbor's sake: but if not, at least for your own profit. It is true, the first is the better course: but if you reach not yet unto that height, do it even for this. And let no man seek his own that he may find his own; and bearing in mind that neither voluntary poverty nor martyrdom, nor any other thing, can testify in our favor, unless we have the crowning virtue of love; let us preserve this beyond the rest, that through it we may also obtain all other, both present and promised blessings; at which may we all arrive through the grace and mercy of our Lord Jesus Christ; Whom be the glory world without end. Amen.
Source: Homilies on First Corinthians (New Advent)