Is the «lntensional Logic» Truly Intensional? Starting from an analysis of a concept as «course-of-values» in Grundgsetze (the Basic Laws of Arithmetic) of Frege, the A. proposes a new characterization of intensionaI equality vs extensional equality. This opposition belongs to a project for defining clearly the duaiity intensioniextension by means oÏ mathematical anà logic tools (combinatory logic and topology -theories of topoi and sheaves -). This approach is closely connected with an adequate formalization of traditional and classic viewpoints in logic, for instance with Leibnitz's views. It is not clear that the actual «intensionallogic» constructed from the works of Karnap, Church and Montague is connected with the classic and old problem of the intension. The linguistics needs an intensional approach for treatinf examples with negation in natural languages.