The retrospective, textual or ientation of rhetor ic follows from the cardinal function that it accords to commonplaces (topos, locus communis).
That is not a property enjoyed by other important categories: it fails in many topoi for example.
Yet the properties of the effective topos are in many respects quite different from those of a category of sheaves.
These are, at this point, recognizable topoi of cultural studies, and it does no harm to mark their shaping force.
For the moment we might notice only that they share elements of the same topos.
First, the use of labels to designate particular types of material presages the principle of stylistically heterogeneous topoi to create blocks of structure.
But in antiquity, invention is still conceived of and practiced most often as a slight variation on a well-known basis of topoi.
The first performance scene makes liberal use of the topoi of twentieth-century popular music.
