The Carnelian Cube

The carnelian cube of the title is a small red "dream stone" confiscated by archaeologist Arthur Cleveland Finch from one of the workers on the dig he is supervising. Sleeping with it beneath his pillow he finds himself cast into a parallel world as "Finch Arthur Poet" -- who is, indeed, a poet. Finding his life endangered, he discovers he can use the stone to escape into yet another parallel world, and the novel follows his adventures through a succession of such worlds.