But it will be exceedingly desirable to infuse variety into our speech, for in all cases sameness is the mother of satiety.  That will be able to be managed if we not always enter upon our argumentation in a similar manner.  For in the first place it is desirable to distinguish our orations as to their kinds, that is to say, at one time to employ induction, and at another ratiocination.  In the next place, in the argumentation itself, it is best not always to begin with the proposition, nor in every case to employ all the five divisions, nor always to work up the different parts in the same manner, but it is permissible sometimes to begin with the assumption, sometimes with one or other of the proofs, sometimes with both, sometimes to employ one kind of summing up, and sometimes another.  And in order that this variety may be seen, let us either write, or in any example whatever let us exercise this same principle with respect to those things which we endeavour to prove, that our task may be as easy as possible.

And concerning the parts of the argumentation it seems to us that enough has been said.  But we wish to have it understood that we hold the doctrine that argumentations are handled in philosophy in many other manners, and those too at times obscure ones, concerning which, however, there is still some definite system laid down.  But still those methods appear to us to be inconsistent with the practice of an orator.  But as to those things which we think belong to orators, we do not indeed undertake to say that we have attended to them more carefully than others have, but we do assert that we have written on them with more accuracy and diligence.  At present let us go on in regular order to the other points, as we originally proposed.

XLII.  Reprehension is that by means of which the proof adduced by the opposite party is invalidated by arguing, or is disparaged, or is reduced to nothing.  And this sort of argument proceeds from the same source of invention which confirmation employs, because whatever the topics may be by means of which any statement can be confirmed, the very same may be used in order to invalidate it.  For nothing is to be considered in all these inventions, except that which has been attributed to persons or to things.  Wherefore it will be necessary that the invention and the high polish which ought to be given to argumentation must be transferred to this part of our oration also from those rules which have been already laid down.  But in order that we may give some precepts with reference to this part also, we will explain the different methods of reprehension, and those who observe them will more easily be able to do away with or invalidate those statements which are made on the opposite side.