The Rainbow in Ancient Context

At the end of the Flood story, God sets his bow (qeshet)—the rainbow—in the clouds to be a “sign of the covenant between me and the earth” (Genesis 9:13). For the modern reader, the rainbow is an optical phenomenon created by the diffraction of water droplets. But this scientific fact was not known to the ancients, and thus this text understands the rainbow as a supernatural sign. But what exactly does it signify?

The Rainbow as Heavenly Writing

For most cultures in the ancient world, the movement of stars and other celestial phenomena were viewed as “heavenly writing” (shitir shamey in Akkadian). They were signs or omens placed in the sky by the gods, which cryptically communicate the gods’ plans. This is the rationale for astrology, which was invented in Mesopotamia. The rainbow was also viewed as a sign, placed in the heavens by the gods. Like other celestial phenomena, the rainbow could be a good or bad omen, depending on the situation.

In one Mesopotamian astronomical text (called Mul-Apin), the variable is the rainbow’s direction:

“If [the rainbow] is in the south: rain. If in the north: flood. If in the east: rain. If in the west: devastation.”

In the Greek Iliad, the rainbow is similarly viewed as an omen of devastation:

Like a lurid rainbow Zeus sends arching
down to mortal men from the high skies, a sign of war
or blizzard to freeze the summer’s warmth.

In all these cultures, the rainbow was a sign of the divine will. But because its meaning was not obvious, it generally required trained specialists – scholars steeped in omen lore – to decipher the divine message.

God Interprets the Sign as a Message to Himself

The rainbow in Genesis is a sign that reworks the conventional divinatory system. It doesn’t require a specialist to decipher, since God announces its meaning explicitly. And its message is not directed at humans, but at God himself. The message is:

וְלֹא יִהְיֶה עוֹד הַמַּיִם לְמַבּוּל לְשַׁחֵת כָּל בָּשָׂר.

There will never again be waters of the flood to destroy all flesh (Genesis 9:15).

Perhaps surprisingly, the message is intended for its sender, to serve as a reminder of his promise. God says:

וְהָיְתָה הַקֶּשֶׁת בֶּעָנָן וּרְאִיתִיהָ לִזְכֹּר בְּרִית עוֹלָם בֵּין אֱלֹהִים וּבֵין כָּל נֶפֶשׁ חַיָּה בְּכָל בָּשָׂר אֲשֶׁר עַל הָאָרֶץ.

Whenever the bow is in the clouds, I will see it and remember the eternal covenant between God and all living creatures (Genesis 9:16).

The sign is placed in the sky for God to see. Its purpose is to remind Himself of His own plan, which is “written” into this natural phenomenon.

God is his own omen interpreter, and the encrypted meaning is meant for Him. This turns upside down the customary system of omens and their interpretation. Now God himself is the sender, recipient, and omen interpreter. This transformation of the omen system probably reflects the biblical antipathy to omens and other magical practices. With certain restrictions – such as the priestly Urim and Thummim[1] – such divinatory techniques are off limits for humans. The signs of the covenant – the rainbow, circumcision, and the Sabbath – are exceptions, because their meanings are carefully curated by God.

A Weapon in the Sky

A well-known Mesopotamian text provides another background for God’s setting his “bow” in the sky. Hebrew uses the word qeshet for both a bow as a weapon, used with arrows to defeat an enemy, and as a rainbow—the former meaning is primary. Since the Flood story is not about combat, the presence of God’s bow may seem out of place.

The Bow Star in Enuma Elish: Marduk’s Triumph over Tiamat

A scene in the Mesopotamian creation account, the Enuma Elish, may suggest that the rainbow in Genesis is also seen as a military bow. After the warrior-god Marduk uses his mighty bow and arrows to defeat the sea-monster Tiamat, the high god Anu places the bow in heaven as a bright star:

Anu lifted it up in the divine assembly,
He kissed the bow, saying, “It is my daughter!”
With the … name, “Bow-Star,” he made it to shine in the sky,
He fixed its heavenly position along with its divine brothers.

The Bow-Star (kakkab qashti) is probably Sirius, the brightest star in the sky. Like the other stars and planets – and like the rainbow – this star has various meanings as an omen. Its movement in the night sky is part of the “heavenly writing” that the omen specialists interpret. But the meaning in the Enuma Elish is clear – the star is a reminder of Marduk’s victory over Tiamat, through which he became the king of the gods. The brightest star is a celestial memorial of Marduk’s glory.

A Bow of Peace after the Flood

God’s bow in Genesis has a comparable resonance. In the Flood story, God triumphs over chaos. But the chaos in the Flood story is not the rage of the sea-monster, it is rather the violence of all flesh that has corrupted its ways on earth, and which has, as a consequence, corrupted the earth. The Flood is God’s natural agent to cleanse the earth from the violence of bloodshed.

After the waters of the flood have receded, God hangs his bow in the sky – like the Mesopotamian Bow-Star – but the bow is not his triumphant weapon. The rainbow is a sign of peace, of God’s promise that the Flood will never come again. Accordingly, as rabbinic commentators observe, it is pointed away from, not toward, humanity. As Nachmanides (Ramban) comments (Gen 9:12),

וכן דרך הנלחמים להפוך אותו בידם ככה כאשר יקראו לשלום למי שכנגדם. ועוד שאין לקשת יתר לכונן חצים עליו:

It is indeed the way of warriors to invert the instruments of war which they hold in their hands when calling for peace from their opponents. Moreover, that the bow has no rope upon which to bend the arrows.

This is why God places his bow in the sky pointing away from the earth.[2]

God’s placing his bow in the sky is a metaphor – a visual symbol – of his promise to desist from global destruction. It is like Marduk’s bow in the sky, but with a message of peace, not martial glory.

A Sign of the Noahide Covenant

In Genesis, God announces that the rainbow is a sign of his covenant with the earth and all living things. This Noahide covenant has a rich content. It includes rules and reciprocal obligations for God, humans, and animals. Humans may now kill animals for food, but must not eat their life-blood. No-one – humans nor animals – may kill humans, for humans are made in God’s image. These laws regulate violence on earth, and they are incumbent on all living creatures. In return, God promises never again to send a Flood. This is the new harmonious order of the post-Flood era.

The rainbow, as a sign of this covenant, will explicitly remind God of his promise, but it also has implicit meanings to the covenant’s other partners. When humans see the rainbow, they are reassured that God will remember the covenant and keep his promise. Despite the perennial rainstorms, life on earth will continue. Those who see the rainbow are also reminded of the story itself, and how violence and bloodshed led to cosmic destruction, followed by renewal. The ethics of Noah – the man of righteousness who “walked with God” – shows that there is a moral compass even when the world is riven with violence.

A Multivalent Sign

The rainbow is a sign of many things. It is a visual sign of the covenant between God and all living creatures, a glittering and mysterious bridge between sky and earth. It is a sign of peace, reconciliation, and the eternity of moral law. We remember these things – even if not altogether consciously – when the rain lets up and the sun shines through the clouds, creating the momentary wonder of the rainbow. Although we know that the rainbow is a natural effect of light after the rain, it is also a sign of biblical memory in our lives and perceptions.