Nothing finite is self-contained: it refers beyond itself for its determinations, for its being what it is, and for its existence. Nothing finite. This is true. A thing is what it is by not being what it is not. Omnis determinatio est negatio. (Spinoza)
Theodor Adorno (Negative Dialektik, Suhrkamp Verlag, S. 109), however, removes the qualifier: he thinks this reference beyond itself is true of everything and that Vermittlung is dafür lediglich ein anderes Wort, that "Mediation is just another word for it."
Nothing is immediate. All is mediated. But what about the system of mediating items? What mediates it? Or is it absolute?
Hegel begat Marx, Marx begat the Frankfurt School which begat cultural (as opposed to 'classical' economic ) Marxism which begat or perhaps is the mess we are now in.
Metaphysically, our mess results from the denial of the Absolute.