"..the Rembrandt whom Constantijn Huygens had discovered was driven constantly to measure himself against the mark others had set: his Amsterdam teacher Pieter Lastman; his Leiden friend and rival Lievens;.. ..Most of all, though, and for an entire decade, Rembrandt measured himself compulsively against 'the prince of painters and the painter of princes': Peter Paul Rubens. To become singular, Rembrandt had first to become someone's double."