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 voice said, Cry. The same divine herald as in Isaiah 40:3.
And he said, What shall I cry? "He" - one of those ministers or prophets (note, Isaiah 40:1) whose duty it was, by direction of "The voice," to 'comfort the Lord's afflicted people with the promises of brighter days.'
All flesh is grass. The connection is, All human things, however goodly, are transitory: God's promises alone are stedfast (Isaiah 40:8; Isaiah 40:15; Isaiah 40:17; Isaiah 40:23-24); this contrast was already suggested in Isaiah 40:5, "All flesh ... the mouth of the Lord." 1 Peter 1:24-25, applies this passage distinctly to the Gospel word of Messiah (cf. John 12:34; James 1:10). By the manifestation of Yahweh's glory at Christ's second advent all human glory shall be shown to be as grass, and God's honour shall be fully vindicated. This truth is spiritually already vindicated in the justification of the sinner only through faith in Christ, that none should glory in the flesh (1 Corinthians 1:23; 1 Corinthians 1:29-31).