Now the employment of persuasive speeches is directed towards a judgement; for when a thing is known and judged, there is no longer any need of argument. And there is judgement, whether a speaker addresses himself to a single individual and makes use of his speech to exhort or dissuade, as those do who give advice or try to persuade, for this single individual is equally a judge, since, speaking generally, he who has to be persuaded is a judge; if the speaker is arguing against an opponent or against some theory, it is just the same, for it is necessary to make use of speech to destroy the opposing arguments, against which he speaks as if they were the actual opponent; and similarly in epideictic speeches, for the speech is put together with reference to the spectator as if he were a judge. Generally speaking, however, only he who decides questions at issue in civil controversies is a judge in the proper sense of the word, for in judicial cases the point at issue is the state of the case, in deliberative the subjects of deliberation. We have already spoken of the characters of forms of government in treating of deliberative rhetoric, so that it has been determined how and by what means we must make our speeches conform to those characters.
Now, since each kind of Rhetoric, as was said, has its own special end, and in regard to all of them we have gathered popular opinions and premises whence men derive their proofs in deliberative, epideictic, and judicial speeches, and, further, we have determined the special rules according to which it is possible to make our speeches ethical, it only remains to discuss the topics common to the three kinds of rhetoric. For all orators are obliged, in their speeches, also to make use of the topic of the possible and impossible, and to endeavor to show, some of them that a thing will happen, others that it has happened. Further, the topic of magnitude is common to all kinds of Rhetoric, for all men employ extenuation or amplification whether deliberating, praising or blaming, accusing or defending. When these topics have been determined, we will endeavor to say what we can in general about enthymemes and examples, in order that, when we have added what remains, we may carry out what we proposed at the outset. Now, of the commonplaces amplification is most appropriate to epideictic rhetoric, as has been stated; the past to forensic, since things past are the subject of judgement; and the possible and future to deliberative.