Institutio Oratoria

Apollodorus says the same thing when he states that a question must either lie in things external, [*](e.g. circumstantial evidence. ) which give play to conjecture, or in our own opinions: the former he calls πραγματικός the latter περὶ ἐννοίας The same is said by those who employ the terms ἀπροληπτὸς [*](ἀπροληπτός lit. = unpresumed. ) and προληπτικός, that is to say doubtful and presumptive, by this latter term meaning those facts which are beyond a doubt.

Theodorus agrees with them, for he holds that the question is either as to whether such and such a thing is really so, or is concerned with the accidents of something which is an admitted fact: that is to say it is either περὶ οὐσίας or περὶ συμβεβηκότων For in all these cases the first basis is conjectural, while the second belongs to one of the other classes. As for these other classes of basis, Apollodorus holds that there are two, one concerned with quality and the other with the names of things, that is to say a definitive basis. Theodorus makes them four, concerned with existence, quality, quantity and relation.