The scribes of Mesopotamia had a patron, and by the first millennium BCE he had quietly become one of the most popular gods in the country. Nabu — Nebo in the English Bible, from the Aramaic form — is the son of Marduk and Sarpanitu, husband of Tashmetu, and lord of Borsippa, whose temple the Ezida stood a few hours' walk from Babylon. His emblem is the plainest in the whole tradition: a stylus, wedge-tipped, standing upright on a shrine, sometimes with a clay tablet beside it. In a pantheon of maces, dragons and lightning forks, one god's badge is a writing implement.
Writing down what has been decided
His function is precisely defined and worth stating carefully, because it is not the same as decreeing. The destinies are fixed by the senior gods; Nabu records them. He is the keeper of the tablet on which the year's fates are entered, and prayers ask him to write the petitioner's name for long days — a request phrased as an entry in a ledger. In an administrative civilisation, the god who holds the pen is not a subordinate figure, and the theology reflects a plain institutional truth: the decision is not real until the scribe writes it.
That is also why he acquired custody of the Tablet of Destinies in later texts, an object earlier associated with Enlil and won back by Ninurta. The document migrated to the god of documents.
The New Year, by boat
At the akitu festival his statue travelled from Borsippa to Babylon by river and canal, was received in procession, and took part in the ceremonies in which the year's fates were determined — after which he returned home, with his marriage to Tashmetu celebrated as part of the cycle. A poem survives in which the two of them speak to each other in alternating voices during that festival, and it is unexpectedly tender: she asks him to shut the door of the bedchamber, and asks his permission to go with him to the garden.
Nimrud, and a treaty in his temple
The Assyrians built Ezida temples of their own, and the one at Kalhu — Nimrud — produced one of the most important finds in Assyriology. In 1955 excavators working in that temple recovered tablets of the succession treaty of Esarhaddon, the oath sworn by vassal rulers in 672 BCE to accept Ashurbanipal as king, complete with a long and famously vivid curse section. Copies had been deposited in the god's throne room, which is exactly where a legally binding text belonged: with the god of writing, under his protection, in the room where his statue stood. A further copy found at Tell Tayinat in Turkey in 2009 confirmed the pattern.
The scribes themselves were devoted to him personally. Colophons — the sign-off lines at the end of a tablet giving the copyist's name and the date — regularly include a formula such as trust in Nabu, and the tablets of Ashurbanipal's great library at Nineveh carry dedications to Nabu and Tashmetu. The man who assembled the collection that preserved Gilgamesh was doing it, in his own account, as an act of piety to this god.
In the Bible, and in half the royal names
Isaiah stages a scene of defeat in which Bel bows down and Nebo stoops, their images loaded onto animals and carried into captivity — a deliberate inversion of the New Year procession, where the gods are carried in triumph. That is a prophet who knew how the festival looked.
More pervasively, his name is the first element in a series of kings the Bible names constantly. Nebuchadnezzar is Nabu-kudurri-usur, "Nabu, protect my heir"; Nabopolassar is Nabu-apla-usur, with the same verb; Nabonidus is Nabu-na'id, "Nabu is praised"; the general Nebuzaradan carries it too. Every one of those names is a small prayer to the scribe god, and their frequency is a fair measure of how popular he had become in Babylonia's last centuries.
The longest career in the pantheon
His cult outlasted almost everything around it. In 268 BCE the Seleucid king Antiochus I had a cylinder inscribed in Akkadian recording his restoration of the Ezida at Borsippa, in the traditional form and the traditional language — a Macedonian Greek performing the duties of a Babylonian king for a Babylonian god, and, as it happens, the last royal building inscription in Akkadian anyone has found. Further west, at Palmyra, a sanctuary of Nabu was built and enlarged in the first and second centuries CE, and Aramaic-speaking populations across Syria carried his name in personal names into the Roman period.
His planet is Mercury, the swift one closest to the sun, and Mercury's later astrological character — communication, commerce, writing, the intellect — is inherited rather than invented. The horoscope tradition that assigns writing and speech to Mercury is repeating an equation first made by Babylonian scholars who had a specific god of the stylus to assign it to.
Things worth checking about him
Was he originally Babylonian at all?
Probably not. His name looks Semitic, from a root meaning to call or announce — the same root behind the Hebrew nabi, prophet — and there is no trace of him in Sumerian material. He appears in Mesopotamia in the Old Babylonian period, apparently arriving from the west with Amorite populations, initially as Marduk's minister rather than his son. The promotion to son, and the vast expansion of his cult in the first millennium, are developments that can be watched happening in the sources.
Is Mount Nebo named after him?
It is a reasonable suggestion and it cannot be demonstrated. The mountain in Moab from which Moses is shown the promised land, and the Moabite town of Nebo, may take their names from this god — the region was within the range of Aramaean religion — but a Semitic root that also produces ordinary words leaves the etymology open. Treat it as plausible and unproven, which is more than most confident internet answers will tell you.
Why did the god of scribes end up outranking his own father in popularity?
Because piety and precedence are different measurements. Marduk remained the head of the pantheon and the state god, but personal names, private prayers and votive objects in the Neo-Babylonian period lean heavily toward Nabu, and the class that produced almost all our written evidence had a professional stake in him. There is a caution buried in that: the surviving record was written by his devotees, so his apparent dominance may partly be a sampling effect — the same problem that shapes what we know about the whole tradition.