[Sidenote: _Denotes any one of a class._]

188. The most frequent use of the indefinite article is to denote
any one of a class or group of objects: consequently it belongs to
singular words; as in the sentence,--

Near the churchyard gate stands _a_ poor-box, fastened to _a_
post by iron bands and secured by _a_ padlock, with _a_ sloping
wooden roof to keep off the rain.--LONGFELLOW

[Sidenote: _Widens the scope of proper nouns._]

189. When the indefinite article precedes proper names, it alters
them to class names. The qualities or attributes of the object are
made prominent, and transferred to any one possessing them; as,--

The vulgar riot and debauchery, which scarcely disgraced _an
Alcibiades_ or _a Cæsar_, have been exchanged for the higher
ideals of _a Bayard_ or _a Sydney_.--PEARSON

[Sidenote: _With abstract nouns._]

190. _An_ or _a_ before abstract nouns often changes them to half
abstract: the idea of quality remains, but the word now denotes only
one instance or example of things possessing the quality.

[Sidenote: _Become half abstract._]

The simple perception of natural forms is _a delight_.--EMERSON