Oswald Spengler first showed that every macroculture can be conceived of as an accretion of signs representing in various contexts a single abstract Prime Symbol. But this semiotic model of culture is not confined to the so-called 'great civilizations'; it is applicable to every culture. In seeking a typology of Prime Symbols (and hence, a semiotic typology of cultures), we show that that the Peircean Categories Firstness, Secondness, and Thirdness (including the 'degenerate' Categories Firstness of Secondness, Firstness of Thirdness, and Secondness of Thirdness) are exemplified in the great range of cultural semiotic types, and that, because of their universality and generality, these Categories are the best semiotic lens through which cultural Prime Symbols can be understood.