Tàpies created his lithographs at Erker Press for the first time in 1963 and continued this activity until shortly before his death. Over 200 lithographs, some woodcuts, and several bibliophile books in collaboration with writers such as Max Hölzer, Martin Heidegger, Alexander Mitscherlich, and Joseph Brodsky were produced. His work emphatically referred to the freedom of Catalonia and Catalan intellectual life, and the liberation from authority. His sign language (ciphers, crosses, etc.) is not to be understood literally, but rather as initials, or the encryption of secret messages. Everything remains open to interpretation. Tàpies’s pictorial puzzles are not meant to be solved. Added to this is his tendency towards the mundane, the honest, and the trivial, expressed in ordinary materials and matters (dust, sand, rags, foot, arm, book, bed, etc.). No artist was as intensively nurtured in the Erker Gallery over the next four decades as he was. Several writings by and about him were published, and the catalogues of his graphic works were translated into German and French.