knows all that Harry knows

"Maybe it's the hot tub," I suggested.
"I saw that you'd never experienced one," Lasciel said. She dipped a toe into the pool and smiled. "I have, often. Do you like it?"
"It's okay," I said, and tried to look like I didn't think it was just about the nicest thing ever for an aching and tired body. "You know what I know, eh?"
"I exist within your mind," she said. "I see what you see. Feel what you feel. I learn what you learn-and quite a bit more besides."
"What is that supposed to mean?" I said.
"That I can do you a great deal of good," she said. "I have the knowledge and memory of two thousand years of life upon this world, and infinite thousands outside it. I know many things that could be of use to you. I can advise you. Teach you secrets of your craft never known to mortalkind. Show you sights no human has ever seen. Share with you memory and image beyond anything you could imagine."


Dead Beat Chapter 25, Page 223-224