For a period of time in the 60s, 70s, and 80s, abstract book covers dominated nonfiction publishing. This blogger had long believed that the covers were created under the influence of psychotropic drugs, and now thanks to the following video we can all see what the cover designers were seeing all those years ago.
A tip: you might want to turn the sound off. It gets incredibly annoying after about a minute.
P.S. Am I the only one who secretly wishes these covers were available as animated GIFs?