From the AC:DM CD Lore
The Explorations of Alatar Locke
Alatar Locke was the first great human explorer in these vast lands of Dereth. He was the first to chart the Direlands, the first to delve into the Halls of Lost Light, and discovered the Empyrean “Floating City” at least a decade before any other Isparian encountered it. He also, as he endlessly reminded the intelligentsia, coined the term “Empyrean.”
Locke was, we fear, lost before Lifestones rose. Or perhaps, being a restless spirit, he found some way of leaving these tame shores, and now travels abroad the myriad seas and lands of this world Auberean.