Seth L. Sanders offers a history of first-millennium scribes through their heavenly journeys and heroes, treating the visions of ancient Mesopotamian and Judean literature as pragmatic things made by people. He presents each scribal culture as an individual institution via detailed evidence for how visionary figures were used over time. The author also provides the first comprehensive survey of direct evidence for contact between Babylonian, Hebrew, and Aramaic scribal cultures, when and how they came to share key features. Rather than irrecoverable religious experience, he shows how ideal scribal "selves" were made available through rituals documented in texts and institutions that made these roles durable. He examines how these texts and selves worked together to create religious literature as the world came to be known differently: a historical ontology of first-millennium scribal cultures. The result is as much a history of science as a history of mysticism, providing insight into how knowledge of the universe was created in ancient times.