One hundred years ago, on Nov. 18, 1922, Marcel Proust breathed his last in Paris at age 51. His death, from pneumonia and a pulmonary abscess, was perhaps the final nail in the coffin of the belle epoque, an age of gentility, civility and artistic achievement that had mostly ended with the outbreak of World War I. At the time, several volumes of Proust’s gargantuan, seven-part novel, “À la recherche du temps perdu” (“In Search of Lost Time”), had yet to be published. Jean Cocteau, arriving to pay tribute to the late author, spotted the manuscript resting on the mantelpiece — a pile of papers “still alive, like watches ticking on the wrists of dead soldiers.”