Institutio Oratoria

The best authorities hold that there are some things in oratory which require proof and others which do not, a view with which I agree. Some on the other hand, as for instance Celsus, think that the orator will not speak on any subject unless there is some question involved in it; but the majority of writers on rhetoric are against him, as is also the threefold division of oratory, unless indeed to praise what is allowed to be honourable and to denounce what is admittedly disgraceful are no part of an orator's duty.

It is, however, universally agreed that all questions must be concerned either with something that is written or something that is not. Those concerned with what is written are questions of law, those which concern what is not written are questions of fact. Hermagoras calls the latter rational questions, the former legal questions, for so we may translate λογικόν and νομικόν.