The use of the indefinite article

The main functions of the indefinite article areclassifying, genericandnumerical.

§ 187. In itsclassifying function the article serves to refer an object to the class or group of objects of the same kind.

We saw a speck in the distance. It was a ship.

I am a school teacher.

Somewhere a telephone began to ring.

The door opened and a man entered.

Janet lived alone in a small shabby house.

He was a man I would be glad to spend half my time in hell with.

The noun preceded by the classifying indefinite article may be accompanied by pre- or postmodifying attributes. The indefinite article is used so long as the reference to the class is preserved, as can be seen from the examples below.

I’ve read a novel.

It is a very interesting novel.

It is a novel by a modem writer.

It is a teenager novel about American boys.

It is an exciting novel which is very suitable for staging.

But: It isthe novel our teacher mentioned at the last lesson.

Though mostly used with counts the indefinite article may be used in the classifying function with non-counts, unique and proper nouns.*

* For details see § 192, 198, 201.

The moon rose early.

It was a very pale siver moon.

§ 188. In itsgeneric function the indefinite article implies that the object denoted by the noun is spoken of as a representative of the class, and therefore what is said about the thing, animal, person, or notion mentioned, refers to any object of the same kind, as in:

An oblong has four sides, a triangle has three sides.

A tram runs on rails, a bus does not.

A horse has four legs.

A sonnet is a poem of fourteen lines.

A library is a collection of books.

The noun preceded by the generic indefinite article may be modified by an attribute which restricts the class represented by the object mentioned or narrows the scope of reference, but does not individualize it.

A complex sentence has two or more clauses.

A man who looks after the books in a library is called a librarian.

The indefinite article in its generic function is often used in proverbs and sentences expressing a general truth.

A friend in need is a friend indeed.

An elephant never forgets.

As a man sows, so he shall mow.

With the nouns in the plural in this case no article is used. It should be noted that the generic function of the indefinite article, though akin to the classifying function, is different not only in its meaning, but also in its role in the process of communication. In the majority of cases a noun with the indefinite article in its generic function is the starting point of the utterance, whereas a noun with the indefinite article in its classifying function used as subject or predicative presents a new item of information, which is the most important part of the utterance.

§ 189. In itsnumerical function the indefinite article retains its original meaning of the cardinal numeral one.

The Indian summer returned for a day.

Of course I won’t say a word.

An apple a day keeps the doctor away.

A stitch in time saves nine.

The numerical function of the indefinite article is evident with nouns denoting units of measure (time, distance, length, weight, etc.): 60 miles an hour, ten shillings a yard. The wireless had become a ton weight. We walked a mile or two.

The function of the indefinite article is also numerical in noun phrases with an ordinal numeral as premodifier, where the article suggests the meaning one more, another:

In this final chapter, we come to a third way in which one may view these parts of the sentence.

The indefinite article in its numerical function may signal a change in the meaning of a non-count making it a count. Thus an ice-cream, a coffee, a tea, a beer, a whisky, etc. mean a portion of, a glass of, a pint of, etc.:

David has ordered a second whisky.

The three main functions of the indefinite article are interrelated, one of them predominating in the context. Thus in the sentence I’ve bought a new dictionary the function of the article is classifying. The numerical idea is implied, but it is not conspicuous enough. If the speaker is interested in number he must say: I’ve bought one dictionary or I want only one dictionary.

On the other hand when the article is used in its numerical sense, the classifying function coexists with the numerical function. Thus in the proverb An apple a day keeps the doctor away the idea of number (one apple, one day) goes together with the idea of class (a kind of fruit, a unit of time),

In the generic function the ideas of oneness and class are combined, but there is no reference to a specific existing thing, person or notion. If we say A triangle has three sides we mean one triangle and a certain class of geometrical figures, but we do not refer the figure drawn on the blackboard to the class mentioned. To express the latter idea we must say The figure is a triangle. The same applies to the following sentences: I wanted to be a doctor where we deal with a classifying meaning of the article, but A doctor is an intelligent man - with generic.

§ 190. There are a number of set expressions with the indefinite article. In most of them the main functions of the indefinite article can be seen.

at a time at a glance as a result (of) as a whole	to be (to feel) at a loss to have a mind (to do something) to have a good time to have a headache (a toothache, a sore throat)
in a good (evil) hour in a hurry(but: in haste) in a fury in a low voice in a whisper	It is a pity It is a pleasure It is a shame What a shame! What a pity!
at a distance of... (but: in the distance) at a depth(but: in the depth) at a speed of...	They were much of a size Birds of a feather flock together. many a time (not once, on many occasions) many a man (not one)