THIRTY YEARS BEFORE his death in 1957, there had ceased to be any doubt of Constantin Brancusi's status as a modernist master. He devoted a long life to distilling extremes of formal perfection from a narrow range of motifs. This perfection is never frozen: it always contains some organic character, an affinity to life and therefore to change. "I never seek what to make a pure or abstract form," Brancusi said. "Timelessness,'' "wholeness,'' "essence,'' "aliveness": such words inescapably recur in what has been written about him over the past 70 or 80 years. They are well-worn tokens, rubbed smooth by use,...

