This new collection of critical essays on science fiction and fantasy literature features the following pieces: "Setting Ideas in Space, Time, and Infinity," "The Necessity of Science Fiction," "The British and American Traditions of Speculative Fiction," "The Biology and Sociology of Alien Worlds," "Cosmic Perspectives in Nineteenth-Century Literature," "An Introduction to Alternate Worlds," "Adolf Hilter: His Part in Our Struggle: (A Brief Economic History of British SF Magazines)," "The Battle of Dorking and Its Aftermath," "The Science in Science Fiction," "The Siren Song of Sexuality: The Mythology of Femmes Fatales," "What We Know About Vampires," "A Brief History of Vampires," and "A Brief History of Werewolves."