1.218 'a' and 'an' with uncount nouns

Although you do not normally use determiners with uncount nouns, you can use 'a' or 'an' with an uncount noun when it is modified or qualified.

• A general education is perhaps more important than an exact knowledge of some particular theory.
• She had an eagerness for life.
• Everything went on with a friendliness that was uncommon in such circles.