The artwork of Joseph Beuys was provocative in his time. Although he was very successful on the international art scene and on the art market, the larger public is still bewildered by his Fat Chair or his installations and his performances. The article shows the evolution of his artwork from classical materials (stone, steel) to soft materials (animals, products of animals) and further to his concept of "social sculpture" and to programmatic diagrams (with words and graphics). A special point of interest is the transition towards language (phonic and conceptual), the philosophy of art exposed in his drawings, and diagrams and the relation between art and science in his artwork.