FoursomeBy: Carolyn Burke A captivating, spirited account of the intense relationship among four artists whose strong personalities and aesthetic ideals drew them together, pulled them apart, and profoundly influenced the very shape of twentieth century art. New York, 1921: acclaimed photographer Alfred Stieglitz celebrates the success of his latest exhibitionthe centerpiece, a series of nude portraits of his soon to be wife, the young Georgia O'Keeffe. The