What you hold in your hands is more than a book. If we are lucky, it is a revolution.
So begins Harlan Ellison's introduction to his 1967 science fiction anthology, Dangerous Visions. A collection of original, previously unpublished stories by more than thirty authors, established talents (Lester del Rey, Theodore Sturgeon, Philip K. Dick) as well as rising stars (Larry Niven, Roger Zelazny, J.G. Ballard), Dangerous Visions was intended as a showcase for stories too provocative, too experimental, or simply too offensive to find publication anywhere else - intended, in Ellison's words, to "shake things up":
This book ... was conceived out of a need for new horizons, new forms, new styles, new challenges in the literature of our times. If it was done properly, it will provide these new horizons and styles and forms and challenges. If not, it is still one helluva good book filled with entertaining stories.
It is unsurprising, given the cultural milieu of 1967, that "new horizons" turns out largely to mean "more sex". The contributors did their best to find taboos and break them, with stories about sadism (Robert Bloch's "A Toy For Juliette"), homosexuality (Poul Anderson's "Eutopia"), and incest (Sturgeon's "If All Men Were Brothers, Would You Let One Marry Your Sister?"). Samuel Delany even invents a brand-new, space-age perversion for "Aye, and Gomorrah...".

There are experiments in form and style as well. Several of the authors in the collection (particularly Ballard, Delany, and Ellison himself) were key figures in the "New Wave" of science fiction - a movement that sought to bring the techniques of literary modernism into SF, while bringing SF into the mainstream of literature. But some of the best stories in the collection are also the most traditional - Niven's "The Jigsaw Man", a gruesome hard-SF story about the social consequences of organ tranplantation, is still gripping forty years later, while the obtrusive puns and stream-of-consciousness sprawl of Philip Jose Farmer's "Riders of the Purple Wage" now seem tediously self-indulgent.

In the years since Dangerous Visions was published most literary taboos have been repeatedly broken, if not stomped on, and the New Wave has come, and (more or less) gone. That the anthology is still worth reading for other than historical reasons is due to the number of good (even classic) stories collected in it. Two won Hugos, one ("Gomorrah") received a Nebula; they are, if no longer shocking, still well-written, often thought-provoking stories. Ellison again:

Each story is almost obstinately entertaining. But each one is filled with ideas as well. Not merely run-of-the pulp ideas you've read a hundred times before, but fresh and daring ideas; in their way, dangerous visions.

A second volume, Again, Dangerous Visions, was published in 1972, with stories by Ursula Le Guin, Ray Bradbury, and Kurt Vonnegut, Jr., among others. A third volume, Last Dangerous Visions, was planned but has never been published.

Ellison, Harlan, ed. Dangerous Visions. New York: Doubleday & Company, 1967.