In the answers to these questions a positive understanding of the problematic of the world will be reached for the first time, the sources of our failure to recognize it will be exhibited, and the ground for rejecting the traditional ontology of the world will have been demonstrated.
[101] The world and Dasein and entities within-the-world are the ontologically constitutive states which are closest to us; but we have no guarantee that we can achieve the basis for meeting up with these as phenomena by the seemingly obvious procedure of starting with the Things of the world, still less by taking our orientation from what is supposedly the most rigorous knowledge of entities. Our observations on Descartes should have brought us this insight.
But if we recall that spatiality is manifestly one of the constituents of entities within-the-world, then in the end the Cartesian analysis of the 'world' can still be 'rescued'. When Descartes was so radical as to set up the extensio as the praesuppositum for every definite characteristic of the res corporea, he prepared the way for the understanding of something a priori whose content Kant was to establish with greater penetration. Within certain limits the analysis of the extensio remains independent of his neglecting to provide an explicit interpretation for the Being of extended entities. There is some phenomenal justification for regarding the extensio as a basic characteristic of the 'world', even if by recourse to this neither the spatiality of the world nor that of the entities we encounter in our environment (a spatiality which is proximally discovered) nor even that of Dasein itself, can be conceived ontologically.
C. The Aroundness of the Environment1 and Dasein's Spatiality
In connection with our first preliminary sketch of Being-in (See Section 12), we had to contrast Dasein with a way of Being in space which we call "insideness" [Inwendigkeit] . This expression means that an entity which is itself extended is closed round [umschlossen] by the extended boundaries of something that is likewise extended. The entity inside [Das inwendig Seiende] and that which closes it round are both present-at-hand in space. Yet even if we deny that Dasein has any such insideness in a spatial receptacle, this does not in principle exclude it from having any spatiality at all, but merely keeps open the way for seeing the kind of spatiality which is constitutive for Dasein. This must now be set forth. But inasmuch as any entity within-the-world is likewise in space, its spatiality will have an ontological connection with the world. We must therefore determine in what sense space is a constituent for that world which has in turn been characterized as an item in the structure of Being-in-the-world. In particular
1 'Das Umhafte der Umwelt'. See our note 1, p. 93, H. 65 above,