The theory of the progressive production of language in the early times of society, and its gradual improvements in the more civilized ones, may be readily induced from the preceding pages. In the commencement of Society the names of the ideas of entire things, which, it was necessary most frequently to communicate, would first be invented, as the names of individual persons, or places, fire, water, this berry, that root; as it was necessary perpetually to announce, whether one or many of such external things existed, it was soon found more convenient to add this idea of number by a change of termination of the word, than by the addition of another word. As many of these nouns soon became general terms, as bird, beast, fish, animal; it was next convenient to distinguish them when used for an individual, from the same word used as a general term; whence the two articles _a_ and _the_, in our language, derive their origin. Next to these names of the ideas of entire things, the words most perpetually wanted in conversation would probably consist of the names of the ideas of the parts or properties of things; which might be derived from the names of some things, and applied to others which in these respects resembled them; these are termed adjectives, as rosy cheek, manly voice, beastly action; and seem at first to have been formed simply by a change of termination of their correspondent substantives. The comparative degrees of greater and less were found so frequently necessary to be suggested, that a change of termination even in our language for this purpose was produced; and is as frequently used as an additional word, as wiser or more wise. The expression of general similitude, as well as partial similitude, becomes so frequently used in conversation, that another kind of adjective, called an adverb, was expressed by a change of termination, or addition of the syllable ly or like; and as adjectives of the former kind are applied to substantives, and express a partial similitude, these are applied to verbs and express a general similitude, as to act heroically, to speak boldly, to think freely. The perpetual chain of causes and effects, which constitute the motions, or changing configurations, of the universe, are so conveniently divided into active and passive, for expressing the exertions or purposes of common life, that it became particularly convenient in all languages to substitute changes of termination, instead of additional nouns, to express, whether the thing spoken of was in a state of acting or of being acted upon. This change of termination betokening action or suffering constitutes the participle, as loving, loved; which, as it expresses a property of bodies, is classed amongst adjectives in the preceding pages.