It is a common error to suppose that there was once but one or a few languages, from which all others have been derived. The reverse is the case. Within the historic period, the number of languages has been steadily diminishing. We know of scores which have become extinct, as many American tongues; others, like the Celtic, are in plain process of disappearance. We can almost predict the time when the work and the thought of the world will be carried on in less than half a dozen tongues, if indeed that many survive as really active.
If we take a comprehensive survey of the grammatical structure of all known tongues, we are cheered by the discovery that they can be divided into a few great classes or groups. The similarities of each group are not in words or sounds, but in the plan of “expressing the proposition,” or placing words together in a phrase to convey an idea.
This may be accomplished in one of four ways:
1. By _isolation_. The words representing the parts of the phrase may be ranged one after another without any change. This is the case in the Chinese and the languages of Farther India.
2. By _agglutination_. The principal word in the phrase may have added to it or placed before it a number of syllables expressing the relations to it of the other ideas. Most African and North Asian tongues are agglutinative.
3. By _incorporation_. The accessory words are either inserted within the verbal members of the sentence, or attached to it in abbreviated forms, so that the phrase has the appearance of one word. Most American languages belong to this type.
4. By _inflection_. Each word of the sentence indicates by its own form its relation to the main proposition. All Aryan and Semitic idioms are more or less inflected.
These distinctions have great ethnographic interest. They almost deserve to be called racial traits. Thus, the inflected languages belonged originally solely to the European race; the isolating languages are still confined wholly to the Sinitic branch of the Asian race; the incorporative languages are found nowhere of such pure type and so numerous as in the American race; while the agglutinative type is that alone which is found in independent examples in every race.