Mnemosyne, the personified power of Memory, has a precise and central role in Orphic eschatology through the Bacchic-Orphic gold tablets. The 'Mnemosyne' class of tablets, of which the Hipponion leaf of about 400 BCE is the earliest, instructs the soul descending to Hades to pass by the spring on the right beside the white cypress - the water of Lethe, forgetfulness - and to go on to the cold water flowing from the Lake of Memory. There the guardians ask the soul who it is, and it must reply that it is a child of Earth and starry Heaven and parched with thirst; on drinking Memory's water it retains itself and travels the sacred road that the other initiates and bacchoi walk. Preserving memory rather than surrendering to oblivion is thus the very mechanism of Orphic salvation, and Mnemosyne, honoured also in the Orphic Hymns, presides over it.