appears the most acute argument of the kind, that alone has possessed itself of the general name as its own peculiar distinction.  Its kinds are these:—­“Can you fear this man, and not fear that one?”—­“You condemn this woman, against whom you bring no accusation; and do you say that this other one deserves punishment, whom you believe to deserve reward?”—­“That which you do know is no good; that which you do not know is a great hindrance to you.”

XIV.  This kind of disputing is very closely connected with the mode of discussion adopted by you lawyers in reply, and still more closely with that adopted by philosophers, as they share with the orators in the employment of that general conclusion which is drawn from inconsistent sentences, which is called by dialecticians the third mood, and by rhetoricians an enthymeme.  There are many other moods used by the rhetoricians, which consist of disjunctive propositions:—­“Either this or that is the case; but this is the case; then that is not the case.”  And again:—­“Either this or that is the case; but this is not the case; then that is the case.”  And these conclusions are valid, because in a disjunctive proposition only one alternative can be true.  And from those conclusions which I have mentioned above, the former is called by the dialecticians the fourth mood, and the latter the fifth.  Then they add a negation of conjunctive propositions; as, “It is not both this and that; but it is this; therefore it is not that.”  This is the sixth mood.  The seventh is, “It is not both this and that; but it is not this; therefore it is that.”  From these moods innumerable conclusions are derived, in which nearly the whole science of dialectics consists.  But even those which I have now explained are not necessary for this present discussion.

XV.  The next topic is drawn from efficient circumstances which are called causes; and the next from the results produced by these efficient causes.  I have already given instances of these, as of the other topics, and those too drawn from civil law; but these have a wider application.

There are then two kinds of causes; one which of its own force to a certainty produces that effect which is subordinate to it; as, “Fire burns;” the other is that which has no nature able to produce the effect in question, though still that effect cannot be produced without it; as, if any one were to say, that “brass was the cause of a statue; because a statue cannot be made without it.”  Now of this kind of causes which are indispensable to a thing being done, some are quiet some passive, some, as it were, senseless; as, place, time, materials, tools, and other things of the same sort.  But some exhibit a sort of preparatory process towards the production of the effect spoken of; and some of themselves do contribute some aid to it; although it is not indispensable; as meeting may have supplied the cause to love; love to crime.  From this description of causes depending on one another in infinite series,