MADRID.- The artistic career of Pierre-Auguste Renoir (1841-1919), one of the leading figures of Impressionism, is characterised by an all-absorbing passion for painting that led him to achieve great renown and popularity among his contemporaries. The outstanding group of 31 works by the artist, which are the finest among the collection of paintings by Renoir assembled by the American collector Robert Sterling Clark (1877-1956), founder of the Sterling and Francine Clark Institute (Williamstown), will be displayed at the Prado in the first monographic exhibition to be held on the artist in Spain. The core of the collection of paintings from the Clark Institute originates in the large group of Impressionist works assembled by Sterling and Francine Clark over the course of four decades. For the Clarks, Pierre-Auguste Renoir represented the quintessence of Impressionism and as a result they acquired more than 35 of his paint