Models: Indomitable Vision

Some models are so famous and sought after that they appear in the works of painter after painter, and their names, like Suzanne Valadon or Kiki of Montparnasse, become almost bywords for an epoch. Their faces and bodies become familiar, delineated as they were by brush after brush, but America's best-known model may well be remembered for one view, and that of the back of her head. Her middle name is the title of one of the all-time bestselling reproductions, Andrew Wyeth's Christina's World.

She was, in fact, Anna Christina Olson, and until...