What does “they shall mount up with wings as eagles” mean?

Who the promise was for

Isaiah 40 opens a new part of the book. Jerusalem has fallen, and Judah’s people live as exiles in Babylon. A voice cries, “Comfort, comfort my people” (Isaiah 40:1). Most scholars date these chapters to about 540 BC, to a later prophet in Isaiah’s tradition; Jewish and Christian tradition hears Isaiah himself, looking far ahead. Near the end of the chapter the exiles’ complaint is put into words: “My way is hidden from Yahweh” (40:27). God has forgotten us.

The answer begins with God, who “doesn’t faint” and “isn’t weary” (40:28). Then it turns to people.

Even the youths faint and get weary, and the young men utterly fall; but 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.

The words underneath

• Wait. The Hebrew verb qavah means to wait with expectation, to hope. Its noun tiqvah, hope, is also the word for the scarlet cord Rahab tied in her window (Joshua 2:18), and it gives Israel’s anthem its name, Hatikvah, “The Hope.” Waiting here is leaning your weight on a line that will hold.
• Renew. The verb means to change or exchange. Those who wait trade spent strength for new. Isaiah uses the same phrase a few verses later, when God calls the nations to “renew their strength” and come to court (41:1).
• Mount up. Literally, they will go up on wing, like eagles.

Eagles, or vultures?

The bird is the nesher. It usually means eagle, but the same word can name the griffon vulture: Micah tells mourners to shave their heads, “Enlarge your baldness like the vulture” (Micah 1:16), and the griffon’s head is nearly bare. Either way, the picture is a huge bird rising on warm air and gliding for hours without seeming to beat its wings. The Bible uses it more than once. God carried Israel out of Egypt “on eagles’ wings” (Exodus 19:4), and a psalm sings of youth “renewed like the eagle’s” (Psalm 103:5). A popular modern story claims that eagles at forty pluck out their own beaks and feathers to live thirty more years. It has no basis in biology, or in the Bible.

Soar, run, walk

Readers often notice that the promise runs downhill. It starts in the sky and ends on foot. Many hear that as the point: soaring is for rare moments, but walking without fainting, one ordinary day after another, is the strength exiles needed most. In verse 30 even the young men fall. In verse 31 the tired who hope keep walking.

Where you have heard it

The King James Version (1611) gave English its best-known wording: “they shall mount up with wings as eagles; they shall run, and not be weary; and they shall walk, and not faint.” In the 1981 film Chariots of Fire, the Scottish runner Eric Liddell, who would not race on a Sunday at the 1924 Paris Olympics, reads this passage from a pulpit while the races go on without him. The verse turns up on posters, gravestones and get-well cards, almost always for the reason it was first spoken: for people who are tired.