Search - A Heritage of Stars

From the classic mid-Seventies era of ecological science-fiction, this novel is among Simak's best, as good a time as A Choice of Gods or Way Station. Post-apocalypse story, plausible characters on a quest (one a witch, another a sage), aliens, beasties and of course the ever-present robot-friend, this time named Rollo, who like characters in Oz can guard all night because he doesn't need sleep.