“A language is said to be dead when no one speaks it any more. It may continue to have existence in a recorded form, of course-traditionally in writing, more recently as part of a sound or video archive (and it does in a sense `live on’ in this way) – but unless it has fluent speakers one would not talk of it as a `living language’. And as speakers cannot demonstrate their fluency if they have no one to talk to, a language is effectively dead when there is only one speaker left, with no member of the younger generation interested in learning it. But what do we say if there are two speakers left, or 20, or 200? How many speakers guarantee life for a language?”

Word Play (1974)
Context: The colors that a speaker "sees" often depend very much on the language he speaks, because each language offers its own high-codability color terms.

Misattributed

Sabhal Mòr Ostaig Lecture (December 19, 2007)

Source: "Discourse in the Novel" (1935), pp. 293-294

"Come Back, Dizzy" (p.187)
So This Is Depravity (1980)

Nobel Prize Lecture (1993)
Context: The vitality of language lies in its ability to limn the actual, imagined and possible lives of its speakers, readers, writers. Although its poise is sometimes in displacing experience it is not a substitute for it. It arcs toward the place where meaning may lie. When a President of the United States thought about the graveyard his country had become, and said, "The world will little note nor long remember what we say here. But it will never forget what they did here," his simple words are exhilarating in their life-sustaining properties because they refused to encapsulate the reality of 600, 000 dead men in a cataclysmic race war. Refusing to monumentalize, disdaining the "final word", the precise "summing up", acknowledging their "poor power to add or detract", his words signal deference to the uncapturability of the life it mourns.

When the Leaves Blow Away (2006), I Still Have a Pony (2007)

Word Play (1974)