+Introductory Hints+.--To express our thoughts with greater exactness we
may need to expand a word modifier into several words; as, A _long_ ride
brought us _there_ = A ride _of one hundred miles_ brought us _to Chicago_.
These groups of words, _of one hundred miles_ and _to Chicago_--the one
substituted for the adjective _long_, the other for the adverb _there_--we
call +Phrases+. A phrase that does the work of an adjective is called an
+Adjective Phrase+. A phrase that does the work of an adverb is called an
+Adverb Phrase+.

As adverbs modify adjectives and adverbs, they may modify their equivalent
phrases; as, The train stops _only at the station_. They sometimes modify
only the introductory word of the phrase--this introductory word being
adverbial in its nature; as, He sailed _nearly around_ the globe.

That we may learn the office of such words as _of, to_, and _at_, used to
introduce these phrases, let us see how the relation of one idea to another
may be expressed. _Wealthy men_. These two words express two ideas as
related. We have learned to know this relation by the form and position of
the words. Change these, and the relation is lost--_men wealth_. But by
using _of_ before _wealth_ the relation is restored---_men of wealth_. The
word _of_, then, shows the relation between the ideas expressed by the
words _men_ and _wealth_.

All such relation words are called +Prepositions+ (Lat. _prae_, before, and
_positus_, placed--their usual position being before the noun with which
they form a phrase).

A phrase introduced by a preposition is called a +Prepositional Phrase+.
This, however, is not the only kind of phrase.