The return of Simak's favorite themes--including robots, esp, and religion--in a thoughtful, gentle, delightfully original treatment. On the remote planet End of Nothing, a colony of advanced robots has established project Vatican-17: the building of an infallible computerized pope whose accumulated wisdom will eventually create a truly universal religion. Gathering data for the omnivorous Pope are the Listeners, humans with esp whose agile minds probe throughout time and space. Also hanging about, on the fringes of the utopian settlement, is reclusive, anachronistic Thomas Decker and his invisible companion, Whisperer, a childlike alien of awesome latent powers. And best of all in this cast of charmers are some wonderfully Simak-ian robots: a beguilingly crusty electronic Pope and his splendidly idiosyncratic robot Cardinals. A lovely place--but then Listener Mary appears to have discovered Heaven (literally); the resulting rancorous dispute (Decker is murdered by a robot, there's a movement to canonize the now-insane Mary) threatens to tear Vatican-17 apart; and the conclusion--involving some secretive, puissant autochthones, trips to weird worlds, a Decker clone, and a trio of peerish, megalomaniac aliens--is carried through with just the right blend of wackiness and humility. Thoroughly enjoyable: one of the best ever from an sf grandmaster whose form has been decidedly variable in recent years.