It is commonly agreed by linguists and anthropologists that the majority of languages spoken now around the globe will likely disappear within our lifetime. The phenomenon known as language death has started to accelerate as the world has grown smaller. This extinction of languages, and the knowledge therein, has no parallel in human history. K. David Harrison's book is the first to focus on the essential question, what is lost when a language dies? What forms of knowledge are embedded in a language's structure and vocabulary? And how harmful is it to humanity that such knowledge is lost forever? Harrison spans the globe from Siberia, to North America, to the Himalayas and elsewhere, to look at the human knowledge that is slowly being lost as the languages that express it fade from sight. He uses fascinating anecdotes and portraits of some of these languages' last remaining speakers, in order to demonstrate that this knowledge about ourselves and the world is inherently precious and once gone, will be lost forever. This knowledge is not only our cultural heritage (oral histories, poetry, stories, etc.) but very useful knowledge about plants, animals, the seasons, and other aspects of the natural world-not to mention our understanding of the capacities of the human mind. Harrison's book is a testament not only to the pressing issue of language death, but to the remarkable span of human knowledge and ingenuity. It will fascinate linguists, anthropologists, and general readers.