Those Gentle Voices: A Promethean Romance of the Spaceways by George Alec Effinger
Warner Books, 1976
Price I paid: 90¢
From Wolf 359 the signals came—proof that man wasn’t the only intelligent life form in the universe. And when Earth’s first interstellar expedition located the radio beacon, they also found a human race—so primitive they hadn’t even discovered the spear, or fire.
If Commander Leigh hadn’t had such fun becoming the Great God Leigh, he might have wondered more about the builders of the radio beacon. And things might have turned out very differently for Earth itself…