Isaiah 40 opens the second major section of the book (chapters 40-66), addressed to God's people facing exile in Babylon. After the warning of chapter 39, God's first word is double comfort: "Comfort, comfort my people," says your God. "Speak comfortably to Jerusalem," for "her warfare is accomplished" and "her iniquity is pardoned." A herald cries, "Prepare the way of Yahweh in the wilderness!" like workers building a royal road. In the New Testament, Matthew 3:3, Mark 1:3, Luke 3:4-6, and John 1:23 identify John the Baptist as this voice, preparing the way for Jesus.
Human strength is like grass, but "the word of our God stands forever." In the New Testament, 1 Peter 1:24-25 quotes this to describe the gospel. Zion becomes a herald of good news: "Behold, your God!" The Lord comes with power, yet "He will feed his flock like a shepherd. He will gather the lambs in his arm." In the New Testament, Jesus calls himself the good shepherd (John 10:11).
The rest of the chapter answers the exiles' despair with a series of questions. Who "has measured the waters in the hollow of his hand"? Nations are "like a drop in a bucket." Idols must be fastened so they won't fall over. "To whom then will you liken God?" He "calls them all by name" to the stars, and "not one is lacking." Israel complained, "My way is hidden from Yahweh," but "The everlasting God, Yahweh, the Creator of the ends of the earth, doesn't faint. He isn't weary. His understanding is unsearchable." The promise follows: "those who wait for Yahweh will renew their strength. They will mount up with wings like eagles. They will run, and not be weary. They will walk, and not faint."