 While in the later tradition the use of metaphors has been seen as a matter of mere decoration, which has to delight the hearer, Aristotle stresses the cognitive function of metaphors. Metaphors, he says, bring about learning (Rhet. III.10, 1410b14f.). In order to understand a metaphor, the hearer has to find something common between the metaphor and the thing the metaphor refers to. For example, if someone calls the old age “stubble”, we have to find a common genus to which old age and stubble belong; we do not grasp the very sense of the metaphor until we find that both, old age and stubble, have lost their bloom. Thus, a metaphor not only refers to a thing, but simultaneously describes the thing in a certain respect. This is why Aristotle says that the metaphor brings about learning: as soon as we understand why someone uses the metaphor “stubble” to refer to old age, we have learned at least one characteristic of old age.