The university course "Introduction to Phenomenological Survey" of the winter semester 1923-24 is the first held by Heidegger in Marburg. Here we present an in-depth analysis of phenomenology which on the one hand affirms for the first time the detachment of Heidegger's thought from Husserl and on the other shows in its fundamental features the hermeneutical character that will mark the same fundamental ontology. This happens in particular through the introduction into a dominant function of the concept of care, which determines the very being of being there and thus the original way for man to be in the world. Finally, the detachment from Husserl and his conception of philosophy takes place on the path of a careful comparison with Descartes, the most extensive that is found in Heidegger's work.

Heidegger's intent is to construct a fundamental ontology that, in the footsteps of the last Husserl, seeks the constitutive nature of the objects of the world starting from the subject and from the transcendental consciousness [87] that somehow makes them possible. Husserl had instead highlighted the need to investigate subjectivity in a non-abstract and generic way, but in relation to the objects of the world and of history: in this sense he had initiated the exploration of the so-called "regional ontologies", ie of those sciences directed to the study of particular aspects or regions of reality, such as logic or mathematics, from an a priori point of view, ie on the basis of their ideal essences. Husserl's attempt to give concreteness to the transcendental subject, however, according to Heidegger was not enough, since we must also take into account his finiteness and the drama of his historical existence. In constructing his ontology, that is, the science that describes being and its fundamental structures, Heidegger believes that we must start from the subject who asks the question of what being is, that is, man. Man has had a problematic relationship with the definition of being, eventually conceiving it as "objectivity", as a simple presence, as the quality for which different objects or entities are placed before me (ob-jecta in Latin). This definition does not take into account man himself, to whom objects are present, but which is not a mere presence in the world, but a taking "care" of it, an action aimed at the future continuously working towards a goal. In fact, according to Heidegger, the existence of man essentially means transcendence, but at the same time towards the world, in order to shape and design it. Man is therefore not a presence but a project, or alternatively a being (Dasein), [90] being in the world, as an inextricable knot of situations in which he finds himself.

If we want to be how to design, the conception of the being of objects, or of "intramundane entities" also changes: these are no longer presences that subsist independently of us, as it induces us to believe the scientific method, but they come seen as tools according to our project. A project that consists precisely in the "preoccupation" of such instruments, taking care of it in the Latin sense of the term, a task that man, by its nature, has towards them. Moreover, even the presumed objectivity with which the technique says to look at them, is actually in function of their instrumentality or usability. Because each instrument cooperates with other instruments in view of a broader horizon which is the ultimate end to which they must serve. , they must be understood within a totality, in the light of the overall world created and unified by the man who pursues his projects. This means that the being of these intramundane entities is given by the fact that there is man: he is the man who makes them come to being.



This result, which in some ways brings Heidegger closer to transcendental idealism and to phenomenological consciousness, for which he was the subject to create the object, is now led by Heidegger to his own need to connect it to the concreteness of existence. . The fact, in fact, that by designing the world makes it come to being as transcendental consciousness, is found to be in turn "designed": he himself is a project thrown (Geworfenheit); it is born and dies without having decided it, and it is limited by its finiteness. The Dasein, therefore, on the one hand denotes freedom (as transcendence), on the other hand, however, this same freedom entails accepting the conditions in which it is going to be expressed (immanence).

Since every project is limited by death, it finds itself lowered into a temporal dimension, a crossroads of past, present and future. And since, as we have seen, intramundane objects come to being through that historical-temporal project that is man, we can say that being is given in time; a concept, this, already of neo-Platonic and Augustinian derivation, for which Being not only "is", but precisely "we give", "happens", revealing itself within the horizon of history, where what will be is destined to fall into what has been, and to whose destiny man is called to lend loyalty. Heidegger will later say: "The future is the origin of history. [...] The beginning is still. It is not behind us, like an event long past, but facing us, before us. The beginning, inasmuch as it is that which is greatest, precedes all that is about to happen and thus has already passed beyond us, above us ". [98] Heidegger's further reflections on the consonance between Being and time are unfinished because of the impossibility of having an adequate linguistic terminology that was not inherited from traditional metaphysics.