With the Isu Aletheia's simulation, Keeper's Insight were stele located within the Isu realms of Elysium, the Underworld and Atlantis.
During the Peloponnesian War, the Spartan misthios Kassandra entered the simulations in order to learn to better use the Staff of Hermes Trismegistus, and finding the Keeper's Insights was a key to this.[1]
Finding each of the Insights led Kassandra to enhance some of her abilities.[1]