A Brief History of the English Language and Literature, Vol. 2
THE PERIODS OF ENGLISH.
1. +Dead and Living Languages.+-- A language is said to be dead when it is no longer spoken. Such a language we know only in books. Thus, Latin is a dead language, because no nation anywhere now speaks it. A dead language can undergo no change; it remains, and must remain, as we find it written in books. But a living language is always changing, just like a tree or the human body. The human body has its periods or stages. There is the period of infancy, the period of boyhood, the period of manhood, and the period of old age. In the same way, a language has its periods.
2. +No Sudden Changes-- a Caution.+-- We divide the English language into periods, and then mark, with some approach to accuracy, certain distinct changes in the habits of our language, in the inflexions of its words, in the kind of words it prefe