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.