Foundation and Earth

Golan Trevize has picked the fate of the human race, and he picked Galaxia: a single living organism spanning the galaxy, where all worlds, all creatures and even the sand underfoot share one consciousness. He chose on instinct and cannot explain it. Before he can trust the decision, he needs the fact the Galaxy has forgotten, which is where humanity began.

His search for Earth begins with two companions. Janov Pelorat is a historian, and Bliss belongs to Gaia, a planet that already thinks as a group mind. Earth has been wiped from libraries and archives so thoroughly that many doubt it ever existed.

The trail leads first to Comporellon, which claims to be the oldest inhabited world. After that it runs out to the abandoned Spacer planets: Aurora, Solaria and Melpomenia. Each holds a piece of the answer, and each gives the travelers a reason to leave quickly.

This is science fiction built as a quest, moving from planet to planet with one question driving each stop. It is the fifth Foundation novel and follows directly from Foundation's Edge, so it suits readers who have already met Trevize. It is the last book in the series' internal chronology, and it ties the Robot, Empire and Foundation novels into one future history. Doubleday published it in 1986.