All argumentation is reprehended when anything, whether it be one thing only, or more than one of those positions which are assumed, is not granted, or if, though they are granted, it is denied that the conclusion legitimately follows from them, or if it is shown that the very kind of argumentation is faulty, or if in opposition to one form and reliable sort of argumentation another is employed which is equally firm and convincing.  Something of those positions which have been assumed is not granted when either that thing which the opposite party says is credible is denied to be such, or when what they think admits of a comparison with the present case is shown to be unlike it, or when what has been already decided is either turned aside as referring to something else, or is impeached as having been erroneously decided, or when that which the opposite party have called a proof is denied to be such, or if the summing up is denied in some one point or in every particular, or if it is shown that the enumeration of matters stated and proved is incorrect, or if the simple conclusion is proved to contain something false.  For everything which is assumed for the purpose of arguing on, whether as necessary or as only probable, must inevitably be assumed from these topics, as we have already pointed out.

XLIII.  What is assumed as something credible is invalidated, if it is either manifestly false, in this way:—­“There is the one who would not prefer riches to wisdom.”  Or on the opposite side something credible may be brought against it, in this manner—­“Who is there who is not more desirous of doing his duty than of acquiring money?” Or it may be utterly and absolutely incredible, as if some one, who it is notorious is a miser, were to say that he had neglected the acquisition of some large sum of money for the sake of performing some inconsiderable duty.  Or if that which happens in some circumstances, and to some persons, were asserted to happen habitually in all cases and to everybody, in this way.—­’Those men who are poor have a greater regard for money than for duty.’  ’It is very natural that a murder should have been committed in that which is a desert place.’  How could a man be murdered in a much frequented place?  Or if a thing which is done seldom is asserted never to be done at all, as Curius asserts in his speech in behalf of Fulvius, where he says, “No one can fall in love at a single glance, or as he is passing by.”

But that which is assumed as a proof may be invalidated by a recurrence to the same topics as those by which it is sought to be established.  For in a proof the first thing to be shown is that it is true, and in the next place, that it is one especially affecting the matter which is under discussion, as blood is a proof of murder in the next place, that that has been done which ought not to have been, or that has not been done which ought to have been and last of all, that the person accused was acquainted with the