Comfort
The first two verses of Isaiah 40. give the key-note of the second part of the prophecy of Isaiah. The great theme of this section is Jesus Christ in His sufferings, and the glory that shall follow in the Davidic kingdom. (See "Christ in O.T.," sufferings,) Genesis 4:4 ; Hebrews 10:18 glory,; 2 Samuel 7:8-15 ; Zechariah 12:8 Since Israel is to be regathered, converted, and made the centre of the new social order when the kingdom is set up, this part of Isaiah appropriately contains glowing prophecies concerning these events. The full view of the redemptive sufferings of Christ (e.g. Isaiah 53) leads to the evangelic strain so prominent in this part of Isaiah. (e.g. Isaiah 44:22-23 ; Isaiah 55:1-3 ).
The change in style, about which so much has been said, is no more remarkable than the change of theme. A prophet who was also a patriot would not write of the sins and coming captivity of his people in the same exultant and joyous style which he would use to describe their redemption, blessing, and power. In John 12:37-44 quotations from Isaiah 53 and Isaiah 6 are both ascribed to Isaiah.
Verse Meaning
As chapter1began with a command ( Isaiah 1:2), so does this second major part of Isaiah"s prophecy. In both places the Word of God is prominent, and in both places Israel is God"s people ( Isaiah 1:3). [source][source][source]
The God of Israel commanded His mouthpieces, especially Isaiah , to comfort His covenant people. Forms of the Hebrew word translated "comfort" appear13times in chapters40-66. One writer believed the comforters were the Jewish exiles in Mesopotamia who called out to the city of Jerusalem (v.2): announcing its revival, rebuilding, and rehabilitation, following the exile. He saw chapters40-55 predicting the Jews" return to Judah from Babylon following the exile, not an eschatological return from all over the earth. [1][source]
This is the language of covenant ( Isaiah 37:35; cf. Exodus 6:7; 2 Samuel 10:2; Jeremiah 16:7). We may imagine a heavenly court scene in which God issued this command (cf. 1 Kings 22:19). The double imperative "Comfort" suggests emotional intensity. "Keeps saying" is a better translation than "says" and stresses the importance of this message. [source][source][source]
Context Summary
Isaiah 40:1-8 - The Cry Of Jehovah's Herald
Voices are ever speaking to us from the infinite; let us heed them.
(1.) There is the voice of forgiveness, Isaiah 40:2. Are you truly penitent? Have you put away your sin? Have you meekly accepted the chastening rod? Then be of good cheer, this promise is for you. The time of hard service as a conscript (the literal rendering) is accomplished, your iniquity is pardoned, you have received double for all your sins. God speaks comfortably to your heart, that you may be able to comfort others as He does you, 2 Corinthians 1:4.
(2.) The voice of deliverance, Isaiah 40:3-4. Between Babylon and Canaan lay a great desert of thirty days' journey with mountain ranges, yawning gulfs. But when God arises to deliver His children, "who cry day and night unto Him," crooked places straighten out, rough ones become smooth, and mountains disappear.
(3.) The voices of decay, Isaiah 40:6-8. The one herald, speaking from his observation of human mortality, describes man and his glory as the "flower of the field." But in contrast to this, another voice seems to break in with the eternal word of God, which stands forever. The precepts, promises, and invitations of the gospel are as sure as God's throne, 1 Peter 1:25. [source]
Chapter Summary: Isaiah 40
1The promulgation of the Gospel 3The preaching of John Baptist foretold 9The preaching of the apostles foretold 12The prophet, by the omnipotence of God 18And his incomparableness 26Comforts the people