In the early days of pulp publication, the artwork provided a literal depiction of the stories' content. Take the famous 1927 Frank R. Paul Amazing Stories "War of the Worlds" cover (it, and many of the other covers I'll mention, is in the slideshow below). The cover for a tale about Martians attacking the Earth shows... well, Martians attacking the Earth. These early sci-fi themes seem easily enough articulated: a general sense of anxiety about technology and space paired with a fear of invasion by The Other. After World War II, the anxiousness and fear remained, magnified by threat of nuclear conflict. Directed towards the Baby Boomers, who were already becoming a formidably large market, material similar to pre-war science fiction was repackaged in a fresh way for its young audiences. As the author and sci-fi expert Robert Horton said in an interview, "...there was a giant new youth culture that emerged in the 1950s, and those kids wanted different kinds of stories, just for them."

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The 1960s marked a new, more-mature era for sci-fi novel art. Then-director of Penguin Books' cover art, Germano Facetti, moved away from cartoonish images of rocket ships and space men by using famous modern artists to convey a mood or tone rather than a literal rendering of the plot. In doing so, he helped legitimize a genre that was still struggling for seriousness and opened the door for even further experimentation. By using images by established artists like Paul Klee, Max Ernst, and Wassily Kandinsky, Facetti was visually connecting these genre novels to a tradition of Western avant garde and high culture. You might not learn anything about the plot of the book from looking at the cover, but at least you would feel smart. These modernist '60s covers conveyed seriousness but sacrificed earlier eras' humor and sense of juvenile wonder. That sterility wouldn't last past the middle of the decade.

Still as abstract as their High Art predecessors, the late '60s novel covers playfully incorporated counterculture elements that would have been unthinkable even 10 years earlier. Take the Robert Heinlein book The Puppet Masters: In its second, 1963, Signet edition, the cover shows a dark but still cartoonish rendering of what looks like a giant space craft. The image is somewhere between the juvenile magazine illustration of the '50s and the abstractions of the early '60s. But by the third edition, in 1970, the cover consists of a partially nude woman standing jauntily in front of two naked men in the foreground, while the background appears to be a tie-dyed "fabric" looking pattern. It's abstract, artistic, playful, sexual, and edgy. It's also confident, almost to the point of being naive: a perfect cover to encapsulate hippiedom's apex in the moment just before Watergate.