The Greek word kanṓn (orig. craftsman’s ‘measure’, ‘standard’) had a range of meanings in Antiquity, all of which referred to a generally valid norm. In art, for instance, it denoted from around the time of Polyclitus (5th century BCE) the proportion theory of the human body. In music, beginning with the Pythagoreans (5th century BCE) it was a twelve-part measuring instrument for determining the intervals. In epistemology from Democritus (4th century BCE) it was the sense …