As to the kind of words used, we may begin with the common adjectives telling the characteristics of an object. If a chemist discovers a new substance, he cannot describe it to others without telling its qualities: he will say it is solid, or liquid, or gaseous; heavy or light; brittle or tough; white or red; etc.
Again, in pointing out an object, adjectives are used; such as in the expressions "this man," "that house," "yonder hill," etc.
Instead of using nouns indefinitely, the number is limited by adjectives; as, "one hat," "some cities," "a hundred men."
The office of an adjective, then, is to narrow down or limit the application of a noun. It may have this office alone, or it may at the same time add to the meaning of the noun.
Substantives.
140. Nouns are not, however, the only words limited by adjectives: pronouns and other words and expressions also have adjectives joined to them. Any word or word group that performs the same office as a noun may be modified by adjectives.
To make this clear, notice the following sentences:—
Pronoun.
If he be thankful for small benefits, it shows that he weighs men's minds, and their trash.—Bacon.
Infinitives.