Should the constitution of mathematical idealities be considered as a subjective activity of construction? This talk addresses the notion of operation, seen as a fundamental trait of the essential historicity of the mathematical thought. The notion of operation is considered the leading thread in the context of the pure morphology of meanings (Formale und transzendentale Logik, § 16 c), which corresponds to pure symbolical thought. Choosing such a trait implies taking into account the operative meaning of signs (Pradelle 2020) as recognized also by the French philosopher Jean Cavaillès while criticizing the Husserlian approach (Cavaillès 1947b). How should the notion of operation be understood? Beginning with the texts of 1891 (collected in Husserliana XII) wherein Husserl reflects on the role of operations and axiomatic systems, we will then take into account Dedekind’s thought (in the Habilitationsschrift of 1854 and in Dedekind 1872 and 1888) and the interpretation offered by Cavaillès (Cavaillès 1938a, 1938b, 1947a). We aim to argue in favour of a noematic-ideal sense of the notion of operation and to show how it should be considered a fundamental principle of the essential historicity of mathematics.