The Anubis Gates, a time-travel fantasy. Guy is part of a group that goes back to see Coleridge lecture, gets stuck in 1810 London. That much is pretty predictable. All the surround, why, and whither is not. Having fun with it.
Interesting bit of trivia: Powers and a college friend made up a poet William Ashbless during their college years and submitted more or less nonsense free verse to what they felt were less-than-picky outlets.
In this book, written some fifteen years later, Powers brings Ashbless in as a minor Romantic Poet. AND his friend, unknowing also published a novel in 1983 using William Ashbless.
I read Power's
Dinner at the Deviant's Palace many years ago and enjoyed it. I got that book when I did a friend a fair sized favor and he said "What can I do for you?"
I said "Just find me some really odd books." And he did. This was one. Another was one of M. John Harrison's Viriconium novels. The third was a fantasy from the 70s placed in Ancient Crete, but I can't for the life of me remember the name. He did well on his end of the bargain