What makes a picture a picture? Franz Erhard Walther, who was honored with a Golden Lion at the 2017 Venice Biennale, took the idea of what an image is supposed to be and turned that concept upside down. At the end of the 1950s, he did this with a touch of nothingness, or to be more precise, with an entire group of works: the Leeren Fl chen (Empty Surfaces). However, these surfaces in fact prove not to be empty at all. To the contrary, the minimal traces that they reveal are loaded with the potential for the viewer, as the creator of inner images, to cast his or her own projections. Thus, Franz Erhard Walther's statement, "the images are in your head," can be taken as programmatic for these Leeren Fl chen. In these works, the image is no longer just material matter. Instead, the work demands an active viewer who adds to it the element of his or her own imagination. The viewer therefore becomes an integral component of the work, the images only become complete in the mind of the viewer. In an extraordinary stroke of serendipity for the field of art history, the works that are reproduced in this catalogue for the first time had been considered lost, but now have resurfaced after several decades. Although they were misunderstood and rejected at the time of their production, these early works helped initiate a paradigm shift that later would culminate in his famous 1.?Werksatz, the work with which Franz Erhard Walther became known internationally when it was exhibited at the Museum of Modern Art, New York in 1969.