For all flesh is as grass - That is, all human beings, all men. The connection here is this: The apostle, in the previous verse, had been contrasting that which is begotten by man with that which is begotten by God, in reference to its permanency. The forher was corruptible and decaying; the latter abiding. The latter was produced by God, who lives forever; the former by the agency of man, who is himself corruptible and dying. It was not unnatural, then, to dwell upon the feeble, frail, decaying nature of man, in contrast with God; and the apostle, therefore, says that “all flesh, every human being, is like grass. There is no stability in anything that man does or produces. He himself resembles grass that soon fades and withers; but God and his word endure forever the same.” The comparison of a human being with grass, or with flowers, is very beautiful, and is quite common in the Scriptures. The comparison turns on the fact, that the grass or the flower, however green or beautiful it may be, soon loses its freshness; is withered; is cut down, and dies. Thus, in Psalms 103:15-16;
“As for man, his days are as grass;
As a flower of the field, so he flourisheth;
For the wind passeth over it and it is gone,
And the place thereof shall know it no more.”
So in Isaiah 40:6-8; a passage which is evidently referred to by Peter in this place:
“The voice said, Cry.
And he said, What shall I cry?
All flesh is grass,
And all the goodliness thereof is as the flower of the field.
The grass withereth,
The flower fadeth,
When the wind of Jehovah bloweth upon it:
Surely the people is grass,
The grass withereth,
The flower fadeth,
But the word of our God shall stand forever.”
See also James 1:10-11. This sentiment is beautifully imitated by the great dramatist in the speech of Wolsey:
“This is the state of man; today he puts forth.
The tender leaves of hope, tomorrow blossoms,
And bears his blushing honors thick upon him.
The third day comes a frost, a killing frost,
And - when he thinks, good easy man, full surely.
His greatness is a ripening - nips his root,
And then he falls.”
Compare the notes at Isaiah 40:6-8.
And all the glory of man - All that man prides himself on - his wealth, rank, talents, beauty, learning, splendor of equipage or apparel.
As the flower of grass - The word rendered “grass,” (χόρτος chortos,) properly denotes herbage; that which furnishes food for animals - pasture, hay. Probably the prophet Isaiah, from whom this passage is taken, referred rather to the appearance of a meadow or a field, with mingled grass and flowers, constituting a beautiful landscape, than to mere grass. In such a field, the grass soon withers with heat, and with the approach of winter; and the flowers soon fade and fall.
The grass withereth, and the flower thereof falleth away - This is repeated, as is common in the Hebrew writings, for the sake of emphasis, or strong confirmation.