The first English translation of selected letters by Italo Calvino (1923-1985) recently appeared from Princeton University Press. Below (in bold), snippets from a 1962 letter to Umberto Eco advising him about a manuscript and how to conceive it more in the up-and-coming postmodern manner.
Postmodernism did not, in fact, become a domineering cultural force among English speakers until three more decades had passed. Calvino's letters show that in the early sixties canny Europeans already perceived and were beginning to understand this new flattened terrain of thought and practice.
... the definition of the avant-gardes, it's too generic and old-fashioned a discourse. Things are more complex than this; there are ten thousand avant-gardes, each different from the next; or rather, we no longer have a tradition and an avant-garde, everything is contemporary.