Book 5
13.12
if it is difficult to refute the statements made by our opponents, we may compare our arguments with theirs, at least if by such a procedure it is possible to prove the superiority of our own. On the other hand, those arguments which rely on their cumulative force must be analysed individually, as for example in the case which I cited above: You were the heir, you were poor and were summoned by your creditors for a large sum: you had offended him and knew that he intended to change his will.
13.13
The cumulative force of these arguments is damaging. But if you refute them singly, the flame which derived its strength from the mass of fuel will die down as soon as the material which fed it is separated, just as if we divert a great stream into a number of channels we may cross it where we will. We shall therefore adapt our method of refutation to the exigencies of our case, now dealing with individual arguments and now treating them in bulk.
13.14
For at times we may include in a single proposition the refutation of an argument which our opponent has constructed of a number of different points. For instance, if the accuser allege that the accused had a number of motives for committing a crime, we may make a general denial of the fact without dealing singly with each alleged motive, because the fact that a man has had a motive for committing a crime does not prove that he has actually committed it.
