John Calvin Commentary Genesis 49:3

"Reuben, thou art my first-born, my might, and the beginning of my strength; The pre-eminence of dignity, and the pre-eminence of power." — Genesis 49:3 (ASV)

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: You, indeed, by nature the first-born, ought to have excelled, since you are my strength and the beginning of my manly vigor; but since you have flowed away like water, there is no longer any ground for arrogating anything to yourself. For from the day of your incest, that dignity which you received on your birthday, from your mother’s womb, is gone and vanished away.

The noun (און), some translate seed, others grief; and interpret the passage this way: Thou my strength, and the beginning of my grief or seed. Those 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 instead have been an antithesis between strength and sorrow.

However, since Jacob is continuously reciting the declaration of the dignity that belongs to the first-born, I do not doubt 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 of where he had fallen from. 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 since we are inclined to flatter ourselves in our vices, scarcely any of us are brought back to a sound mind after we have fallen, unless we are touched with a sense of our vileness. Moreover, nothing is better adapted to wound us than when a comparison is made between those favors 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 purpose is this designed to serve, except that Adam, reflecting within himself how far he has changed from that man who had recently been created according to the image of God and had been endowed with so many excellent gifts, might be confounded and fall prostrate, lamenting his present misery?

We see, then, that reproofs are necessary for us, so that we may be touched to the quick by the anger of the Lord. For thus it happens not only that we become displeased with the sins for which we are now bearing the punishment, but also that we take greater care to diligently guard those gifts of God that dwell within us, lest they perish through our negligence.

Those who refer the “excellency of dignity” to the priesthood, and the “excellency of power” to the kingly office, are, in my opinion, too subtle interpreters. I understand the simpler 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.