Genesis 49:3

3. Reuben, thou art my first-born He begins with the first-born, not for the sake of honor, to confirm him in his rank; but that he may the more completely cover him with shame, and humble him by just reproaches. For Reuben is here cast down from his primogeniture; because he had polluted his father’s bed by incestuous intercourse with his mother-in-law. The meaning of his words is this: Thou, indeed, by nature the first-born, oughtest to have excelled, seeing thou art my strength, and the beginning of my manly vigor; but since thou best flowed away like water, there is no more any ground for arrogating anything to thyself. For, from the day of thy incest, that dignity which thou receivedst on thy birth-day, from thy mother’s womb, is gone and vanished away. The noun (און,) some translate seed, others grief; and turn the passage thus: “Thou my strength, and the beginning of my grief or seed.” They who prefer the word grief, assign as a reason, that children bring care and anxiety to their parents. But if this were the true meaning, there would rather have been an antithesis between strength and sorrow. Since, however, Jacob is reciting, in continuity, the declaration of the dignity which belongs to the first-born, I doubt not that he here mentions the beginning of his manhood. For as men, in a certain sense, live again in their children, the first-born is properly called the “beginning of strength.” To the same point belongs what immediately follows, that he had been the excellency of dignity and of strength, until he had deservedly deprived himself of both. For Jacob places before the eyes of his son Reuben his former honor, because it was for his profit to be made thoroughly conscious whence he had fallen. So Paul says, that he set before the Corinthians the sins by which they were defiled, in order to make them ashamed. (1 Corinthians 6:5.) For whereas we are disposed to flatter ourselves in our vices, scarcely any one of us is brought back to a sane mind, after he has fallen, unless he is touched with a sense of his vileness. Moreover, nothing is better adapted to wound us, than when a comparison is made between those favors which God bestows upon us, and the punishments we bring upon ourselves by our own fault. After Adam had been stripped of all good things, God reproaches him sharply, and not without ridicule, “Behold Adam is as one of us.” What end is this designed to answer, except that Adam, reflecting with himself how far he is changed from that man, who had lately been created according to the image of God, and had been endowed with so many excellent gifts, might be confounded and fall prostrate, deploring his present misery? We see, then, that reproofs are necessary for us, in order that we may be touched to the quick by the anger of the Lord. For so it happens, not only that we become displeased with the sins of which we are now bearing the punishment, but also, that we take greater care diligently to guard those gifts of God which dwell within us, lest they perish through our negligence. They who refer the “excellency of dignity” to the priesthood, and the “excellency of power” to the kingly office, are, in my judgment, too subtle interpreters. I take the more simple meaning of the passage to be; that if Reuben had stood firmly in his own rank, the chief place of all excellency would have belonged to him.