Institutio Oratoria

And

as a matter of fact his work was not designed to deal with humour, but with urbane wit, a quality which he regards as peculiar to this city, though it was not till a late period that it was understood in this sense, after the word Urbs had come to be accepted as indicating Rome without the addition of any proper noun. He defines it as follows:

Urbanity is a certain quality of language compressed into the limits of a brief saying and adapted to delight and move men to every kind of emotion, but specially suitable to resistance or attack according as the person or circumstances concerned may demand.

But this definition, if we except the quality of brevity, includes all the virtues of oratory. For it is entirely concerned with persons and things to deal with which in appropriate language is nothing more nor less than the task of perfect eloquence. Why he insisted on brevity being essential I do not know,