Pablo Picasso is widely considered the greatest artist of the 20th Century; he was also its greatest graphic artist. His published approximately 2,000 different images pulled from metal, stone and other media. The cataloguer of Picasso's prints, Georges Bloch, has observed: "Picasso is truly revealed by following the genesis of his work from one date to another. All his phases and styles, which we use as landmarks, are in reality only successive stages of a continuity that constitutes the phenomenon of Picasso."