Wesensschau. This intuition of essences is a special case of categorial intuition and it is characterized by apodictic evidence. Thus it may solve the question of intuitivity together with the problem of necessary validity. My way to argue for this thesis is to analyze some intuitive steps in simple proofs and point out some rules that enable an implicit variation. Following the traces of the eidetic method in mathematical intuition it turns out that not only in material mathematics like in geometry, but also in formal mathematics, there is a special kind of implicit eidetic variation that serves as the source of intuitivity in proofs." /> Intuition in mathematics - Lohmar Dieter | sdvig press