Another book revisited from my youth. It still was a good yarn, with interesting thoughts on the nature of what we might now call the "Clash of Civilizations". Also particularly amusing for the ways in which the future was both accurately and inaccurately predicted: nuclear power did not prove to be the panacea Asimov thought, and he also didn't anticipate e-mail (capsules with written messages get teleported through space) or the effects of Moore's law on storage (a Galactic Encyclopedia is planned in volumes stored in libraries throughout the galaxy). But it holds up anyway as a story and vision.