All possibilities only attain possibility within history; even the New is historical. Even the Novum of an abolition of private property (which is anticipated by most social utopias, in that no longer topical section which transcends to the final level), even this Novum is not a priori unalterable. It looks very different in the work of the not very liberal Plato than in that of Thomas More, and very different again in his work than in that of Robert Owen. Not even the New itself, in its respective dimension, not even the utopian element, as pertaining to the superstructure, is invariant. The 'future ages' which Jacob shows to his sons on his deathbed are not the same, either in their content or in their concept of the future, as those which the chiliast Joachim of Calabrese had in mind in the thirteenth century, let alone those meant by Saint-Simon. What is invariant is solely the intention towards the utopian, for it is continuously discernible throughout history: yet even this invariance immediately becomes variable when it gets beyond expressing the first word, when it speaks the contents which are always historically varied.
-- Ernst Bloch, "The Principle of Hope. Volume 2", sivu 480. --