This is the close to the last address contained in the Lectures on Negative Dialectics, a volume that compiles a series of lectures given by Theodor W. Adorno in 1965-1966 on questions associated with concerns he would contemplate in his eponymous magnum opus, Negative Dialectics (1966). The Lectures are edited by Rolf Tiedemann and translated from the German by Rodney Livingstone (Cambridge, UK: Polity, 2008, p. 181-2):
“Knowledge, which desires content, is really in search of utopia.
It [utopia], the consciousness of possibility, clings to whatever has not been disfigured. The way to utopia is barred by the possible, never the immediate reality. This is why it always appears abstract in the midst of existing reality.
It is served by thought, a piece of existence that, negative as always, reaches out to that which is not.
Phil[osophy] converges to this point: at the uttermost distance, which alone would be proximity.
It is the prism in which its colour is captured.”