Institutio Oratoria

Above all we must see that we do not contradict ourselves, a slip which is far from rare on the part of spinners of fiction: for some things may put a most favourable complexion on portions of our case, and yet fail to agree as a whole. Further, what we say

In either case the orator should bear clearly in mind throughout his whole speech what the fiction is to which he has committed himself, since we are apt to forget our falsehoods, and there is no doubt about the truth of the proverb that a liar should have a good memory.

But whereas, if the question turns on some act of our own, we must make one statement and stick to it, if it turns on an act committed by others, we may cast suspicion on a number of different points. In certain controversial themes of the schools, however, in which it is assumed that we have put a question and received no reply, we are at liberty to enumerate all the possible answers that might have been given.

But we must remember only to invent such things as cannot be checked by evidence: I refer to occasions when we make our own minds speak (and we are the only persons who are in their secret) or put words in the mouth of the dead (for what they say is not liable to contradiction) or again in the mouth of someone whose interests are identical with ours (for he will not contradict), or finally in the mouth of our opponent (for he will not be believed if he does deny).

Glosses drawn from dreams and superstitions have long since lost their value, owing to the very ease with which they can be invented. But it will avail us little to use glosses in a statement of fact, unless they are consistent throughout the whole of our speech, more especially as certain things can only be proved by persistent assertion.

Take for instance the case of the parasite who claims as his son a young man who has been

But unless every word that he utters reveals an ardent paternal affection, hatred for his wealthy opponent and anxiety on behalf of the youth, who will, he knows, be exposed to serious danger if he remains in the house where he is the victim of such dislike, he will be unable to avoid creating the suspicion that he has been suborned to bring the action.

It sometimes happens in the controversial themes of the schools, though I doubt whether it could ever occur in the courts, that both sides employ the same gloss and support it on their own behalf.