 In other words, this section introduces the logic of quantification, in a way that is familiar to contemporary logic. The propositional logic of the preceding sections is interpreted as true only of elementary, first order propositions, and so extended to higher-order logic by showing how sentences can be presented in “prenex form”, that is with quantifers in intial position preceding a quantifier free matrix. These theorems are familiar now as “quantifier confinement” theorems, of the form of: