The oracle of Trophonios at Lebadeia (Boiotia), among the best documented in Greece, was active from the archaic period to the third century AD. At this oracle, divine revelation was given in the form of a ‘visionary trance’, experienced as a psychic journey or leap of the soul into the world of truth. From the beginning, the cult and legend of Trophonios (and of similar heroes) turned upon the boundary between ‘the other world’ and the here-and-now, and were intimately linked with psychagogy, divination (including iatromancy), and the mysteries. The analysis of each of the oracle's components in the light of ancient mentalities has broadened our understanding of both Trophonios and of Greek divination in general.