Its plot seems outlandish in summary, and adjectives won't do. Perhaps I'd better just say that after one reads it one begins to muse, and the more one muses, the more interesting it gets.
Some pieces click into place.
He would have to have put it there himself before he died. He was hypnotized. But Magnus Eisengrim had just finished explaining that one cannot force the hypnotized to act against their wishes. The stone is phallic. Fifth Business in this case is Dunstable Ramsay, a crumpled old history professor with a wooden leg and an interest in mythology, magic and hagiography, who has just retired after 45 years of teaching in a private Canadian boys' school.