In the last thirty years, the concept of legibility has become a topos in the humanities, referring to the act of reading freed from its usual connection with the written text, and concerning also images, traces, and constellations. No one so deeply understood this ‘non-literal’ reading as Walter Benjamin, whose oeuvre is crossed by the topic of the compenetration and coappartenance of image and text. In his epistemology, mental and material images are intended as things that must be read. This paper offers an interpretation of his concept of legibility through its comparison with the one given by Aby Warburg in his Mnemosyne-Atlas. Both authors wanted to analyze the relationship between image and word to study the language of emotions and gestures. Through the comparison of the two methods emerges a privileged viewpoint to understand legibility as a fundamental epistemological paradigm of Kulturwissenschaft around 1900.