I came across this on a Gaelic forum (Foram na gaidhlig). I thought it so true that I'm passing it on.
Quote from Leanne Hinton Berkeley University in the USA
More broadly, the loss of language is part of the loss of whole cultures and knowledge systems, including philosophical systems, oral literacy and musical traditions, environmental knowledge systems, medical knowledge and important cultural practices and artistic skills. The world stands to lose an important part of the sum of human knowledge whenever a language stops being used. Just as the human species is putting itself in danger through the destruction of species diversity, so might we be in danger from loss of the diversity of knowledge systems.
Tom