For a language is really alive only as long as there is someone to speak it to. When you are the only one left, your knowledge of your language is like a repository, or archive, of your people's spoken linguistic past. If the language has never been written down, or recorded on tape—and there are still many which have not—it is all there is. But, unlike the normal idea of an archive, which continues to exist long after the archivist is dead, the moment the last speaker of an unwritten or unrecorded language dies, the archive disappears for ever. When a language dies which has never been recorded in some way, it is as if it has never been.

p. 2 - How Language Works, 2007