 While Picasso was working on his Proto-Cubist , he visited his friend Ignacio Zuloaga in his studio in Paris and studied El Greco's "Opening of the Fifth Seal" (owned by Zuloaga since 1897).The relation between and the "Opening of the Fifth Seal" was pinpointed in the early 1980s, when the stylistic similarities and the relationship between the motifs of both works were analysed.The early Cubist explorations of Picasso were to uncover other aspects in the work of El Greco