The first thing to realize in studying the English language is that it is primarily (起初) something that is spoken, not written. The introduction of a system of recording thought and speech by writing (and later by printing)was a very important step forward, and without it we should be very largely ignorant (无知的) of the ways of life and the modes(方式) of thought of our ancestors.(祖先).We should be completely shut off from the great minds of the past, and it would be quite impossible for us undertake such a study, since we should have no means of knowing anything about the language of the people who lived in this country five hundred or a thousand years ago, and still less should we be in a position to relate that language to the tongues spoken in other countries. The only means we have of knowing the kind of language used by Julius Caesar or by King Alfred the Great－the words they employed and the grammar of their speech—is by studying such written documents as have survived: and in the main that will be the method employed by future generations when they wish to investigate（调查） the language of our own age. Now because of this necessity of relying on written documents for learning about language, and because reading and writing have come to occupy so large a place in our daily lives, there has grown up a tendency to think of language in terms of the written or printed word. But printing and writing are only substitutes（代替) for speech. In its primary sense language, as its name implies, is oral. Printing and writing have certainly had an influence on the development of language—usually displaying a conservative tendency,（趋势) opposed to too rapid change or innovation;（创新) but in the last resort （求助）what is written is determined by what is said.
Secondly we must realize that in language change is constantly going on. If we look at a passage from Chaucer (who was writing towards the end of the fourteenth century), and compare it with the English that is spoken and written today, it is obvious that the language has altered considerable in the intervening five hundred years or more; and if we go even further back, we find an even greater difference. These facts are really too self-evident to need pointing out. But though this evolutionary（演变) factor is obvious and generally recognized, there is frequently a tendency to assume（假定) that it is a thing of the past, and that, in all 'civilized countries' at least, language has now become more or less fixed and set, so that the English, the French and the German of today will be the English, the French and the German of two centuries hence. This is far from the truth.
In the third place, it should be realized that speech or language is the distinguishing（有区别的) characteristic （特性）of man as such, and is one of the chief attributes（特征) which differentiate him from the other animal species（种类）. Why? The answer is probably to be found in the development of mind. The species which developed mind and personality also developed speech.