Dreams & Divine Revelation
The gods spoke in sleep — commissioning kings, warning of doom, in dreams the learned knew how to read.
Also: dream · dreams · shuttu · dream interpretation · dream omen · Assyrian Dream-Book · Gudea dream · revelation
Dreams were a recognized channel of divine communication. A god might appear in a dream to commission a king to build a temple (as Ningirsu does to Gudea), to warn of coming danger, or to reveal hidden things; ominous dreams foretold the future and could be interpreted by experts using dream-handbooks. Some dreams were clear messages, others cryptic signs requiring decoding, and rituals existed to ward off the evil portended by a bad dream. From royal building-accounts to the dream-omen series, the dream sits alongside divination as a means by which the unseen will of the gods broke through into waking life.
In short
The belief that gods communicate through dreams — commissioning kings, warning of danger, foretelling events — and the learned practice of interpreting them, codified in dream-omen handbooks.
Where it’s found
Gudea's commissioning dream in the Cylinders (ETCSL 2.1.7, in corpus); Dumuzid's ominous dream (ETCSL 1.4.3, in corpus); the Akkadian dream-omen series (akkadian-pending; Oppenheim, The Interpretation of Dreams in the Ancient Near East)
How the idea developed across Sumer, Babylon & Assyria
Divine commissioning dreams are old and royal (Gudea's temple-dream, in corpus); systematic dream-interpretation is codified in the first-millennium dream-omen compendium (the 'Assyrian Dream-Book', Akkadian). Distinguish message-dreams from symbolic omen-dreams.