The mind of man is confined in its operations by the material system it inhabits, and has no modes of communicating with other minds except through the medium of the eye and ear. It is by signs addressed to the eye and by sounds affecting the ear that ideas are communicated and received.

It is by the power of association, which enables us to recall certain ideas together which have been frequently united, that the use of language is gained. The infant finds certain states of mind produced by material objects invariably connected with certain sounds. This is done so often that whenever a certain perception occurs, the sound recurs which has been so often united with it.

If language is correctly defined as "any sound or sign which conveys the ideas of one mind to another," it is probable that children learn language at a much earlier period than is generally imagined. It is impossible to know how soon the infant notices the soft tones of its own voice when happy, or the moaning or shrill sound that expresses its own pain, and by comparing them with those of its mother, learns, through its little process of reasoning, that another spirit has emotions of pleasure and pain corresponding with its own. Nor can we determine how soon these pleasant sounds of the mother's voice begin to be associated with the benignant smile, or the tones of grief with the sorrowful expression, or the tones of anger with the frowning brow.

It seems very rational to suppose that sound, to the infant mind, is what first leads to the belief of the emotions of another mind, by means of a comparison of its own sounds with those originating from another. After this is done, the eye comes in for a share in these offices. The little reasoner, after thousands of experiments, finds the pleasant sound always united with the smiling face, until the object of vision becomes the sign for recalling the idea at first obtained by sound. In gaining the common use of language, we know this is the order of succession. We first learn the sounds that recall ideas, and then, by means of a frequent union of these sounds with some visible sign, the power once possessed simply by the sound is conveyed to the sign. Thus we have words that are sounds and words that are visible signs.

The communion of one spirit with that of others in every-day life is maintained ordinarily through the medium of sounds; but when distance intervenes, or when some record is to be preserved of the thoughts and feelings of other beings, then signs addressed to the eye are employed. In civilized nations, the signs used are a certain number of arbitrary marks, which are arranged in a great variety of combinations, and each combination is employed to recall some particular idea or combination of ideas. These arbitrary signs are called letters, and in the English language there are only twenty-six; yet, by the almost infinite variety of combination of which these are capable, every idea which one mind wishes to communicate to another can be expressed.

A written word is a single letter or a combination of letters used as a sign to recall one or more ideas. It is considered by the mind as a unit or whole thing, of which the letters are considered as parts, and is shown to be a unit by intervals or blank spaces that separate it from the other words of a sentence. The fact that it is considered by the mind as a unit, or a sign separate from all other combinations of letters, is the peculiarity which constitutes it a word. A syllable is a combination of letters which is not considered as a unit, but is considered as a part of a word.

Words are used to recall the ideas of things, qualities, changes, and circumstances. Some words recall the idea of a thing without any other idea connected with it; such are the words mind, ivory. Some words recall the idea of quality simply, such as red, hard, sweet. Some words recall the ideas of change merely, such as motion, action. Some words recall simply the idea of relation or circumstance, such as on, under, about. Sometimes ideas of things, and their actions and relations, are recalled by the same sign; thus wrestler recalls the idea of a thing and its action, and giant of a thing and its relation. Some words recall a variety of ideas; thus the term begone recalls the idea of two things, of the desire of a mind and of its mode of expression.

In the process of learning language, mankind first acquire names for the several things, qualities, changes, and circumstances that they notice, and afterward learn the process of combining these names, so as to convey the mental combination of one mind to another. A person might have names for all his ideas, and yet, if he had never learned the art of properly combining these signs, he never could communicate the varied conceptions of his own mind to another person. Suppose, for illustration, that a child had learned the meaning of the terms cup, spoon, the, put, into, little, my; it would be impossible for him to express his wish till he had learned the proper arrangement of each term, and then he could convey the conception and wishes of his own mind, viz., "Put the spoon into my little cup."

We see, then, how the new combinations of ideas in one mind can be conveyed to another. The two persons must both have the same ideas attached to the same sign of language, and must each understand the mode of combination to be employed. When this is done, if one person sees a new object, he can send to his friend the signs which represent all its qualities, circumstances, and changes arranged in a proper manner. The absent person will then arrange the conceptions recalled by these words, so as to correspond with those of his correspondent.

In all languages, the same word often is used to recall different ideas, and the meaning of words depends often on their mode of combination.