ABSTRACT
Throughout history pictures have displayed an intriguing communicative potential. Common sense values a picture at a thousand words. If a picture were considered a document of language, it would consequently provide some one thousand visual signs, except that the fl uid shapes and contours of pictorial entities make these signs impossible to tally. The boundless wealth of visual signs not only defi es any traditional classifi cation, as by a dictionary, but also challenges the potentially historical nature of visual communication in general: if visual signs change their form each time they represent a two-dimensional sight, they are a reminder of the philosophy of Heraclitus, who found that it is impossible to throw a stone twice into the same river. If the same river also cannot be looked at twice, or photographed twice, how then can the river or its photograph be seen with the eyes of a historian?
