In August of 1949, the subtitle of a Life magazine story on the painter Jackson Pollock asked, “Is he the greatest living painter in the United States?” Over the previous few years, Pollock had gained notoriety—even infamy—for his “drip” technique and the paintings he produced with it. (In 1956, about six months before his death, Time magazine would pin on him the memorable sobriquet of “Jack the Dripper.”) And then, at the height of his fame, he swerved from the path that had brought him such notice, embarkin…