This paper addresses the phenomenological notions of “essence”, “idea” and “eidetic knowledge”; it is structured as follows. In section 1 the authors, the texts and the time frame taken under consideration are specified. Section 2 and 3 deal with the problem of the two-faced nature of the notion of “essence”, which is both the quid of the entity and what the idea of the entity itself tries to capture. In section 4 it is argued that the phenomenologists considered (J. Hering, R. Ingarden, M. Scheler, as well as Husserl) are engaged in two different tasks. On the one hand, the programmatic task of defending the existence of essences and a peculiar kind of epistemic access to them from external criticisms (M. Schlick, P. Natorp). On the other hand, the task to clarify: a) what the individual essence is in general and what the relationship with its corresponding idea amounts to; b) what are the specific types of individual essences and the corresponding ideas. In section 5 it is shown how Scheler: a) has been engaged in the first task, anticipating some of Ingarden’s thesis; b) has contributed to the debate on the individual essence, analyzing entities such as persons.
