Well, she seems absolutely delighted! Well done Aziraphale, pat yourself on the back. Even though she doesn't want a book. That's okay. He can have his own, and she can make conversation. Nice compromise.

"Mmhm, mmhm," he says, nodding enthusisatically, fingers steepled before him. "It's something... a little supernatural, isn't it?" He's sort of assuming, based on her 'old enemy' being an unearthly monster - unless that was all an incredible metaphor. "And I wouldn't worry about single-mindedness, if it's replenishing you. Replenishment is vital, even in dreams." With that he pops a book into existence, an old favorite - the beloved Wicked Bible (if only it were the real thing) - sets it on his knee and begins to read casually. He picks up his tea, holding it ever so daintily by its little handle, and says, "Go on, if you wish, I've read it before."