The return of Simak's favorite themes--including esp, robots & 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 thru time & space. Also hanging about, on the fringes of the utopian settlement, is reclusive, anachronistic Thomas Decker & his invisible companion, Whisperer, a childlike alien of awesome latent powers. Best of all in this cast of charmers are some wonderfully Simakian robots: a beguilingly crusty electronic Pope & 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; & the conclusion--involving some secretive, puissant autochthones, trips to weird worlds, a Decker clone & a trio of peevish, megalomaniac aliens--is carried thru with just the right blend of wackiness & humility. Thoroughly enjoyable: one of the best ever from an sf grandmaster whose form has been decidedly variable in recent years.--Kirkus