54 I.II
Being and Time

1. "In-the-world": In relation to this factor, we have the task of questioning the ontological structure of "world" and of defining the idea of worldliness as such (cf. Chapter Three of this Division).

2. The being [Seiende] which always has being-in-the-world as the way it is. In it we are looking for what we are questioning when we ask about the "who?". In our phenomenological demonstration we should be able to determine who is in the mode of the average everydayness of Dasein ( cf. Chapter Four of this Division).

3. Being in as such: The ontological constitution of in-ness itself is to be analyzed (cf. Chapter Five of this Division). Any analysis of one of these constitutive factors involves the analysis of the others; that is, each time seeing the whole phenomenon. It is true that being-in-the-world is an a priori necessary constitution of Dasein, but it is not at all sufficient to fully determine Dasein's being. Before we thematically analyze the three phenomena indicated individually, we shall attempt to orient ourselves toward a characteristic of the third of these constitutive factors.

What does being-in mean? We supplement the expression being-in right away with the phrase "in the world," and are inclined to understand [54] this being-in [In-Sein] as "being in ... " ["Sein in ..." ]. With this term, the kind of being of a being is named which is "in" something else, as water is "in" the glass, the dress is "in" the closet. By this "in" we mean the relation of being that two beings extended "in" space have to each other with regard to their location in that space. Water and glass, dress and closet, are both "in" space "at" a location in the same way. This relation of being can be expanded; that is, the bench in the lecture hall, the lecture hall in the university, the university in the city, and so on until: the bench in "the cosmos" ["Weltraum"]. These beings whose being "in" one another can be determined in this way all have the same kind of being—that of being present as things occurring "within" the world. Being present "in" something objectively present and the being present together with something having the same kind of being (in the sense of a determinate relation to place) are ontological characteristics which we call categorial. They belong to beings whose kind of being is unlike Dasein.

In contrast, being-in designates a constitution of being of Dasein, and is an existential. Thus, we cannot understand by this the objective presence of a corporeal thing [Körperding] (the human body [Menschenleib]) "in" a being objectively present. Nor does the term being-in designate a spatial "in one another" of two things objectively present, any more than the word "in" primordially means a spatial relation of this kind.1 "In" stems from innan-, to live, habitare, to dwell. "An"

1. Cf. Jakob Grimm, Kleinere Schriften, vol. 7, p. 247.

Martin Heidegger (GA 2) Being & Time (S&S)