by Universe Books, $29.50. The superb collection of early twentiethcentury art owned, if not always appreciated, by the Soviet Union was amassed by a small group of Moscow merchants at a time when neither Paris nor Westernized St. Petersburg saw much good in the likes of Matisse and Picasso. The Moscow patrons were remarkable for their vision. They were also exceptional men, and were supplied with a network of variously daft or distinguished connections. Ms. Kean’s reconstruction of their world, of the reasons for their enthusiastic acceptance of the new painters, and of the effect of their importations on Russian art is fine social as well as aesthetic history.Whitney Kean.