Language death is like no other form of disappearance. When people die, they leave signs of their presence in the world, in the form of their dwellin… - David Crystal

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.

Language may not determine the way we think, but it does influence the way we perceive and remember, and it affects the ease with which we perform mental tasks.

We now know that linguistic change does not operate in such an across-the-board manner. Some speakers introduce the change into their speech before others; some use it more frequently and consistently than others; and some words are affected before others. A more accurate view is to think of a change gradually spreading through the words of a language – a view that is known as a lexical diffusion. At first just a few people use a change sporadically in a few words (commonly occurring words are influenced very quickly); then a large number of words are affected, with the sound gradually being used more consistently; then the majority of the words take up the change.