NEW YORK, N.Y.- Over the course of the next year, Sotheby’s will be offering at auction a cast of each of Henri Matisse’s spectacular bas-relief nudes, known collectively as Les Nus de dos (The Backs). The unprecedented sale of the four monumental bronze sculptures will begin with Matisse’s first incarnation of the form, Nu de dos (1er état), on offer in the 2 November Impressionist & Modern Art Evening Sale in New York (est. $20/30 million*). Conceived in 1908-09 at the culmination of Matisse’s involvement with the Fauves, the sculpture exemplifies the fluidity of line that dominated his paintings from this era. The artist’s later three iterations of this theme, Dos II, Dos III and Dos IV, will be offered individually in the next three consecutive Evening Sales of Impressionist & Modern Art at Sotheby’s: London, February 2012; New York, May 2012; and London, June 2012 (pictured at botto