Beginning Dec. 18, visitors at the Morgan Library and Museum will find a new treasure: a never-before-exhibited, 44- by 57-inch sketch of two figures featured in Pierre-Auguste Renoir’s “The Large Bathers” — a sizable painting created during the artist’s departure from Impressionism late in his career.

“The bold, sensuous lines of this expressive drawing present a different side to the Renoir we know through his paintings,” said the Morgan’s director, Colin B. Bailey, in a statement. “The Morgan’s Drawings Department is renowned for its collection of works that illustrate the creative process, and this drawing gives us a glimpse into the mind of a master.”

Reclining in the foreground of the final version of the painting, the two bathers in the sketch exemplify Renoir’s experimentation with classical nudes and is inspired, in part, by François Girardon’s “The Bath of the Nymphs,” a 17th-century sculpture in Versailles.

The sketch, drafted with white chalk on canvas-mounted paper, is notable not only for the insight it provides into Renoir’s process, but also for its dimensions. While Renoir produced more than 20 studies between 1884 and 1887 while drafting “The Large Bathers,” the sketch acquired by the Morgan is one of only two full-scale model drawings of what would become the final version of the painting.

“Renoir — in an attempt to reconcile this tradition with modern painting — labored over this work for three years, making numerous preparatory drawings for individual figures and at least two full-scale, multi-figure drawings,” reads the Philadelphia Museum of Art’s exhibition label for the finished painting. “Faced with criticism of his new style after completing ‘The Large Bathers,’ an exhausted Renoir never again devoted such painstaking effort to a single work.”

Top Image: Pierpont Morgan's study at the Morgan Library and Museum.