121 I. 3
Being and Time

But in significance itself, with which Dasein is always familiar, there lurks the ontological condition which makes it possible for Dasein, as something which understands and interprets, to disclose such things as 'significations'; upon these, in turn, is founded the Being of words and of language.

The significance thus disclosed is an existential state of Dasein—of its Being-in-the-world; and as such it is the ontical condition for the possibility that a totality of involvements can be discovered.

If we have thus determined that the Being of the ready-to-hand (involvement) is definable as a context of assignments or references, and that even worldhood may so be defined, then has not the 'substantial Being' of entities within-the-world been volatilized into a system of Relations? And inasmuch as Relations are always 'something thought', has not the Being of entities within-the-world been dissolved into 'pure [88] thinking'?

Within our present field of investigation the following structures and dimensions of ontological problematics, as we have repeatedly emphasized, must be kept in principle distinct: 1. the Being of those entities within-the-world which we proximally encounter—readiness-to-hand; 2. the Being of those entities which we can come across and whose nature we can determine if we discover them in their own right by going through the entities proximally encountered—presence-at-hand; 3. the Being of that ontical condition which makes it possible for entities within-the-world to be discovered at all—the worldhood of the world. This third kind of Being gives us an existential way of determining the nature of Being-in-the-world, that is, of Dasein. The other two concepts of Being are categories, and pertain to entities whose Being is not of the kind which Dasein possesses. The context of assignments or references, which, as significance, 'is constitutive for worldhood, can be taken formally in the sense of a system of Relations. But one must note that in such formalizations the phenomena get levelled off so much that their real phenomenal content may be lost, especially in the case of such 'simple' relationships as those which lurk in significance. The phenomenal content of these 'Relations' and 'Relata'

Being and Time (M&R) by Martin Heidegger