Our 4D world is the equivalent of Dante’s Purgatorio which makes passing into the 5D realm entering Paradiso. Dick compares the three-tiered structure he envisions to Dante’s where the lowest realm is isolation, the middle introduces empathy and connection and the upper is full knowledge of the whole self unified with the informational world.
He has a vision of the beings that inhabit the 5D realm and sees them as deaf, ape-like creatures. They communicate using color in a way we can’t fully appreciate with our senses. We are effectively blind to their world, but they stimulated Dick’s phosphenes artificially which allowed him to see Valis.
Because they are deaf our music is fantastical to them. Dick decides they are our friends and we can give them the gift of song. The universal language is math, and music is math made audible.
He has a book idea where one of these beings passes a mathematical pattern to a human who composes music from it without understanding where it came from. When the human finally realizes what is happening he has to make a choice: ultimately exhaust himself by continuing to make music to feed the being’s insatiable desires or live without composing. In the end they make a bargain to trade his music for a gift of their visual language, as color, which destroys his mind.
Dick recognizes the relative viewpoints. The beings see us as gods as they look into our music-filled world. To them our world is paradise. He claims for the first time in his life to be truly enlightened.