As its central tenet, the avant-garde ethos presumes that no contemporary artist is significant unless his work offers a style or structure as novel as it is realized and/or an original insight into the changing human situation in our time. This spirit informs no only positive judgments but negative ones, ruling that not only should the artist not repeat his predecessor's works but also that he should not repeat himself. In this sense, all the truly great artists of the twentieth century were, whether intentionally or not, discernibly avant-garde at some point of their careers; and the history of modern art and literature, in all genres, can be persuasively interpreted as largely a record of avant-garde activity.

On Innovative Art(ist)s (1991)

The other major American artist closest to [Gertrude Stein] is the composer Charles Ives, who was curiously born in the same year, 1874. Likewise declining to earn a living through art, he composed pieces that were for decades unperformed, much as Stein's manuscripts were unpublished. Each received great recognition just before their deaths—1946 for Stein, 1954 for Ives. There is no evidence that they ever met each other. Perhaps the surest way I have of gauging their originality is that I can identify what each of them did with terms that come from my understanding of subsequent avant-garde art, using such epithets as minimalism, simultaneity, uninflected form, etc.; but since such ideas were not known in the early twentieth-century, I can barely imagine what they thought they were doing.

“Gertrude Stein” (2003)