A short story that first appeared in 1958, expanded and polished to a high gloss. A handful of islands in a planetary ocean, Thalassa is a colony derived from a robot seedship sent from Earth centuries ago, just before the sun went nova. With few environmental challenges, the Thalassans have developed a peaceful but stagnant culture. Then a ship arrives from Earth: the huge Magellan, powered by "quantum drive" (it derives energy from the quantum fluctuations of space itself); traveling at the speed of light, Magellan left Earth just before the final nova bearing a million colonists preserved in cold-sleep. Magellan has stopped off at Thalassa on its way to the distant planet Sagan Two in order to renew its shield. (Moving at the speed of light, the ship could be destroyed by the strike of a mere grain of dust, so it carries ahead of it a cone-shaped shield of ice to absorb such impacts.) The story of the interaction between the Thalassans and the crew of Magellan is often an absorbing one, set forth in a supple and pleasingly surefooted narrative, peopled with characters who are well developed but so-so nice even when they're angry. What the book glaringly lacks, like 2010: Odyssey Two (1982), is conflict and drama; Clarke's efforts in that direction--a potential mutiny aboard Magellan, the hitherto undiscovered presense of maybe-intelligent "scorps" (sea scorpions) in Thalassa's oceans--fall flat. Still, there's much to admire here--not least Clarke's dream of civilization without fossilized hatreds and violence--and his vast audience won't be disappointed.