Clinical photography in the late 19th century aimed at unveiling the hidden processes invisible to the clinical eye. Changes in the outer form hinted at deeper lying causes, and decoding these forms was supposed to extend the range of the clinical eye in to the realm of invisibility. Two suppositions supported this hope: the belief that each disease as an ontological entity showed typical exterior signs which allowed a diagnosis at sight, and the technological trust in photography as a precise and objective means of representation superior to the human eye. For a short time, clinical photography seemed to be the 'via regia" of diagnosis. Heinrich Curschmann's Klinische Abbildungen and Ludwig Jankau's periodical Internationale medizinisch-photographische Monatsschrift marked the climax of this development in Germany. Röntgen's discovery and its immediate application in clinical medicine put an end to the optimistic expectations: clinical photography was from now on only one among many different means of documenting clinical signs and findings.