On view at Castelli Gallery, 1046 Madison Avenue, are works by Richard Pettibone, which are composed of multiple canvases. Among these are 'Constantin Brancusi, ‘Newborn,’ 1915, Nine Times,' 2014; 'Andy Warhol, Thirty-two ‘Campbell’s Soup’ Cans, 1961,' 2010; 'Frank Stella, ‘Ouray,’ 1961, Three Times,' 2011; and 'Andy Warhol, ‘Flowers,’ 1965, White-Blue, 16 Variations,' 2011. Arranged as a cohesive unit within each artwork are many paintings of the same subject, varying slightly in size or color. By joining many pieces that differ only by degrees into a single work Mr. Pettibone emphasizes the subtle differences between the parts that constitute the whole. In so doing, the artist calls on viewers to make finer and finer distinctions about what they see.