nouns. For example, examine this:--

The _arts_ differ from the _sciences_ in this, that their power
is founded not merely on _facts_ which can be communicated, but
on _dispositions_ which require to be created.--RUSKIN.

When it is said that _art_ differs from _science_, that the power of
art is founded on _fact_, that _disposition_ is the thing to be
created, the words italicized are pure abstract nouns; but in case _an
art_ or _a science_, or _the arts_ and _sciences_, be spoken of, the
abstract idea is partly lost. The words preceded by the article _a_,
or made plural, are still names of abstract ideas, not material
things; but they widen the application to separate kinds of _art_ or
different branches of _science_. They are neither class nouns nor pure
abstract nouns: they are more properly called _half abstract_.

Test this in the following sentences:--

Let us, if we must have great _actions_, make our own
so.--EMERSON.

And still, as each repeated _pleasure_ tired, Succeeding _sports_
the mirthful band inspired.--GOLDSMITH.

But ah! those _pleasures_, _loves_, and _joys_
Which I too keenly taste,
The Solitary can despise.--BURNS.

All these, however, were mere _terrors_ of the night.--IRVING.