As Halloween approaches, Daniel Stephensen finds himself wondering what else Poe would have written had he not died at age forty, what strange treasures we would have received. The book of Poe's to make him wonder most in this direction is Eureka: A Prose Poem, an ambitious metaphysical investigation into the cosmological principles of what Poe calls the “Universe of Stars.” It is by turns measured and logical, vision-struck and enraptured.