Shora is a world entirely covered by water; here live the all-female Sharers, in perfect ecological harmony with their planet, aboard huge, living, buoyant rafts. The Sharers are biological whizzes but fear and mistrust non-living materials such as stone, metal and ceramic. Shora has no government; issues are decided at extended ""gatherings,"" with news and views promulgated by genetically engineered ""clickflies."" The worst punishment a Sharer can suffer is to be ""Unspoken,"" ostracized. Sharer Merwen, on a fact-finding tour of Shora's sister planet Valedon, meets young malcontent Spinel (the Valans all have suitably rocky names: ""Rutile,"" ""Cyant,"" ""Oolite"") and takes him back to Shora, where he struggles to adjust to Sharer ways. Meanwhile on Valedon, various wars are winding down in preparation for the visit of Malachite, representative of the Patriarch of Torr; the Torran empire is dedicated to preventing the redevelopment of weapons and powers that could trigger another devastating galactic war. But Malachite turns out to be a robot; and, fearing the Sharers' unknown biological capabilities, he orders the Valans to invade and subdue Shora. The Sharers, mentally and philosophically incapable of fighting, react in the only ways open to them: by offering to share their knowledge and culture with the invaders. An impressive hard-cover debut, carefully worked out and richly detailed, but with a number of flaws: the Sharers, an impossibly calm and reasonable bunch; the overcomplicated galactic-war backdrop; the very tight, mechanical plot; and the expressionless prose. The result is intellectually stimulating, but never engages the emotions.