Languages differ not only in being more or less analytic, but in their general modes of classification. That is, not only do they have more or less adequate vocabularies, but in their syntax, their sentence structure, their word forms, they variously organize experience. It is important to note that in these divergent classifications no one of them is more final than another. We are tempted, despite this fact, to think that the grammar, spelling, and phonetics of our own language constitute the last word in the rational conveyance of thought. THE INSTABILITY OF LANGUAGE. Language being a social habit, it is to be expected that it should not stay fixed and changeless. The simpler physiological actions are not performed in the same way by any two individuals, and no social practice is ever performed in the same way by two members of a group, or by two different generations. In this connection writes Professor Bloomfield: The speech of former times, wherever history has given us records of it, differs from that of the present. When we read Shakspere, for example, we are disturbed by subtle deviations from our own habits in the use of words and in construction; if our actors pronounced their lines as Shakspere and his contemporaries did we should say that they had an Irish or German brogue. Chaucer we cannot read without some grammatical explanation or a glossary; correctly pronounced his language would sound to us more like Low German than like our English. If we go back only about forty generations from our time to that of Alfred the Great, we come to English as strange to us as modern German, and quite unintelligible, unless we study carefully both grammar and lexicon.[1] [Footnote 1: Bloomfield: _loc. cit._, p. 195.] There are, in general, three kinds of changes that take place in a language. "Phonetic" changes, that is, changes in the articulation of words, regardless of the meaning they bear. This is illustrated simply by the word "name" which, in the eighteenth century was pronounced ne'm. " Analogic" changes, that is, changes in the articulation of words under the influence of words somewhat similar in meaning. The word "flash," for example, became what it is because of the sound of words associated in meaning, "crash," "dash," "smash." The third process of change in language alters not only the articulate forms of words, not only their sound, but their sense. All these changes, as will be presently pointed out, can easily be explained by the laws of habit early discussed in this book, these laws being applicable to the habit of language as well as to any other.