If languages were uniform and invariable, they might be easier to learn and to use, but their communicative and expressive resources would probably be rather limited. We can only wonder whether such a language would suffice for linguistically creative literary works like João Guimarães Rosa's Grande Sertão: Veredas, or António Lobo Antunes's A Hora dos Lobos, or Mia Couto's Terra Sonâmbula. More likely, a uniform language would be to real language as tic-tac-toe to chess: both games are governed by rules, but chess offers plenty more room for variation.

Language, in fact, is more like a game of chess played by multiple partners who, while abiding by the same general rules, use variants that all along require reinterpretation and accommodation if the game is to proceed. At times the rules in use diverge so sharply – as if some players suddenly decided to try out checker rules – that the game breaks down. More often than not, however, adjustments are made here and there and the match goes on.

It is only by reducing a language to a theoretical construct that we can create the illusion of immutability. Real language varies in time, in geographical space, and in the omnipresent social spectrum. Accordingly, throughout this book we have tried to complement a generic presentation of Portuguese with specific instances of variation. This chapter will take a closer look at how the use of the language relates to social variables.