The song Cave Of Phantom Dreams by Hawkwind is about the god of sleep, Somnus, and the dream world that he rules over. The lyrics describe Iris, the goddess of the rainbow, painting the sky and leading the way to Somnus's cloud-wrapped palace. Somnus is depicted as a peaceful and gentle god who banishes care and refreshes exhaustion. The song goes on to describe the cavern of Somnus's oblivion, where countless herds are gathered to sleep and strengthen themselves on Earth. The master of the cavern is surrounded by phantom dreams, represented as various forms of disguise. Overall, the song creates a dreamlike and mystical atmosphere, exploring the concept of the dream world and the power of sleep. The lyrics paint a vivid picture of Somnus's realm, drawing on Greek mythology to create a sense of wonder and mystery.