In the next place, what the matter in dispute is must be explained, when we come to mention the examination into the excuses which are alleged. And how that is managed has been already stated. But the arrangement which embraces the properly distributed explanation of the facts, ought to have brevity, completeness, conciseness. Brevity is when no word is introduced which is not necessary. This is useful in this sort of speaking, because it is desirable to arrest the attention of the hearer by the facts themselves and the real divisions of the case, and not by words or extraneous embellishments of diction. Completeness is that quality by which we embrace every sort of argument which can have any connexion with the case concerning which we have got to speak, and in this division we must take care not to omit any useful topic, not to introduce any such too late, out of its natural place, for that is the most pernicious and discreditable error of all. Conciseness in arrangement is preserved if the general classes of facts are clearly laid down, and are not entangled in a promiscuous manner with the subordinate divisions. For a class is that which embraces many subordinate divisions as, "an animal." A subordinate division is that which is contained in the class as "a horse." But very often the same thing may be a class to one person, and a subordinate division to another. For "man" is a subordinate division of "animal," but a class as to "Theban," or "Trojan." XXIII And I have been more careful in laying down this definition, in order that after it has been clearly comprehended with reference to the general arrangement, a conciseness as to classes or genera may be preserved throughout the arrangement. For he who arranges his oration in this manner--"I will prove that by means of the covetousness and audacity and avarice of our adversaries, all sorts of evils have fallen on the republic," fails to perceive that in this arrangement of his, when he intended to mention only classes, he has joined also a mention of a subordinate division. For covetousness is the general class under which all desires are comprehended, and beyond all question avarice is a subordinate division of that class.