Words are the factors of speech and the highest development of that faculty. A word may be composed of one or more sounds so articulated as to preclude any interval of time between the utterance of any two of them, as "tune," in which the sounds appear to overlap and blend into each other. A single word may signify more than a single thing, and sometimes will suggest to the mind a category or group of connected thoughts, as "eat" or "telegraph," and such is the value of many of our words. This is especially true of words which combine two roots; but such a combination is usually found only in the higher types of human speech. But in these higher types words bear such relations to each other that we cannot well convey a complete idea with a single word; and hence it is that in the modes of expression used by man, each separate statement consists of two or more words bearing certain relations to each other, and these are often qualified by other words of less importance. This redundancy is due to the higher and more complex modes of thought used by man; and it is on such a state of facts that we have founded that branch of science called grammar, which would be of little use among those forms which occupy the planes of life inferior to man, and it is found of little use among the lower tribes of man, where it does not exist in any written form. Grammar does not make language, but serves as a kind of anchor by which the dialects of human speech are somewhat unified and made more stable; and to this is due in some measure the fact that savage tongues and dialects are more susceptible to change in their structure, while the phonetic basis upon which they rest remains the same. [Sidenote: GRAMMAR AND RHETORIC] In the more refined tongues of human speech, we go beyond that code of laws called grammar and amplify them into rhetoric. This branch of the science of speech could find no place among the lower types, as the words are few from which they may select; and so exact and arbitrary is the meaning of each one, and so uniform the relations, that no great variety of expression can be made with such a limited vocabulary. Their eloquence is in their brevity of speech. But while the types of speech used by the lower primates occupy a plane so low in the scale, they are as truly speech as the vocal organs that produce the sounds are truly vocal organs. Life is life, in what form soever it is found. It is not less real in the mollusc than in the man. The same is true of emotion, of thought, of expression, and of speech. Life, emotion, thought, expression, and speech began in embryo, and have developed co-ordinately with all the faculties possessed by man. They are as dependent upon each other as matter is on force, and as inseparable as light from energy. Speech is the physical manifestation of which thought is the ultimate force; it is a spoke in the chariot-wheels of consciousness; it is the body of which thought is the soul. CHAPTER XX.