Les caracteres perceptifs des objets et la theorie mathematique des groupes

Objects present some perceptive qualities that might be called “objectual” and others that might be called “relational”. Sometimes the same sensorial process generates both, and the psychological process which works the discrimination between these two kinds of perceptive qualities, allows us to single out of reality elements that are constant, notwithstanding the variation of physical conditions, and which we called the “objectual qualities” of objects.