The voice said,
Cry.
And he said, What shall I cry?
All flesh is grass, and all its loveliness is as the flower of the field:
All Commentaries on Isaiah 40:6 Go To Isaiah 40
Augustine of Hippo
AD 430
Both what is being thought of by intelligence and what is sounding out loud in speech is changeable and dissimilar. The first will not remain when you have forgotten it, nor will the second when you stop speaking. But “the Word of the Lord remains forever” and abides unchanged and unchangeable.
