Death Was Their Pilot, Fear Their Fuel
Out Of Infinite Smallness Grew A Gigantic Peril
Find the five keys to Earth’s Freedom
They Brought A New Iceage
Evil Had A Third Eye
I believe that’s called a “monocle”
They ruled the stars — yet knew not how!
Exiles From A Hostile Universe
Robert Silverberg actually wrote Guardian Of The Crystal Gate based on this cover.
“In fact, after I had been part of his staff for six months or so, he paid me the considerable compliment of asking me to write a story around a cover painting that Ed Valigursky, one of his best artists, had just brought in.
The painting showed two attractive young ladies in short tunics fiercely wrestling atop a huge diamond.”
You can read the whole thing here