 In general, how a symbol refers—whether it denotes or exemplifies, what it denotes or which of its features it exemplifies, whether it does so directly or indirectly, literally or metaphorically—depends on the system of symbolization within which the symbol is found. Furthermore, a symbol is the sort of symbol it is—linguistic, musical, pictorial, diagrammatic, etc.—in virtue of its belonging to a symbol system of a certain kind. And symbols differ from each other according to their different syntactic and semantic rules.