By classing science fiction as a branch of fantasy, I make it a subdivision of that vast literary genre that includes Homer’s _Odyssey_, Milton’s _Paradise Lost_, the Norse sagas, _Alice in Wonderland_, much of Poe, and so forth. Placing the emphasis on technology, however, requires science fiction to have a certain systematic content, an underlying rationale of theme. A story about a vampire is pure fantasy; a story that rationalizes vampirism in terms of metabolic phenomena is science fiction. It is the attempt at inducing a willing suspension of disbelief by supplying a plausible scaffolding for the implausible that gives science fiction its identity within the greater realm of fantasy. But because science fiction _is_ a form of fantasy, it is ideally suited for the exploration of drug-related phenomena. A drug is a kind of magic wand; but it is a chemist’s magic wand, a laboratory product, carrying with it the cachet of science. By offering his characters a vial of green pills or a flask of mysterious blue fluid the author is able to work wonders as easily as a sorcerer; and by rigorously examining the _consequences_ of his act of magic, he performs the exploration of speculative ideas which is the essence of science fiction. So in the nineteenth century Robert Louis Stevenson produced _Dr. Jekyll and Mr. Hyde_, Mary Wollstonecraft Shelley devised an elixir of immortality in _The Mortal Immortal_, and H. G. Wells created a whole shelf of drug-related stories, speeding up human motion in “The New Accelerator,” turning beasts into men in _The Island of Dr. Moreau_, depicting an unseeable phantom in _The Invisible Man_. And in the present century the use of mind-altering or mind-controlling drugs has become one of the prime vehicles for the speculations of science-fictionists. In preparing this study of drug themes in science fiction, I have employed the following categorical designations: _Drugs as Euphorics_: Drugs that give pleasure in simple unstructured ways, through release from depression and tension, much as alcohol does in our society (though alcohol is not strictly speaking a euphoric, of course). _Drugs as Mind Expanders_: Drugs that provide “psychedelic” visions of other times or places or that offer a sensation of oneness with the cosmos as a whole; analogous to LSD in our society. _Drugs as Panaceas_: Drugs which, through tranquilizing or neutralizing effects, calm the mind without necessarily inducing euphoria. _Drugs as Mind Controllers_: Drugs that enable one entity to limit or direct the activities or desires of another; analogous to brainwashing, and generally associated with totalitarian activities. _Drugs as Intelligence-Enhancers_: Drugs which have the specific property of extending or amplifying the rational processes of the mind.