It remains to speak of Diction and Thought, the other parts of Tragedy having been already discussed. Concerning Thought, we may assume what is said in the Rhetoric, to which inquiry the subject more strictly belongs. Under Thought is included every effect which has to be produced by speech, the subdivisions being,--proof and refutation; the excitation of the feelings, such as pity, fear, anger, and the like; the suggestion of importance or its opposite. Now, it is evident that the dramatic incidents must be treated from the same points of view as the dramatic speeches, when the object is to evoke the sense of pity, fear, importance, or probability. The only difference is, that the incidents should speak for themselves without verbal exposition; while the effects aimed at in speech should be produced by the speaker, and as a result of the speech. For what were the business of a speaker, if the Thought were revealed quite apart from what he says? Next, as regards Diction. One branch of the inquiry treats of the Modes of Utterance. But this province of knowledge belongs to the art of Delivery and to the masters of that science. It includes, for instance,--what is a command, a prayer, a statement, a threat, a question, an answer, and so forth. To know or not to know these things involves no serious censure upon the poet's art. For who can admit the fault imputed to Homer by Protagoras,--that in the words, 'Sing, goddess, of the wrath,' he gives a command under the idea that he utters a prayer? For to tell some one to do a thing or not to do it is, he says, a command. We may, therefore, pass this over as an inquiry that belongs to another art, not to poetry. XX [Language in general includes the following parts:--Letter, Syllable, Connecting word, Noun, Verb, Inflexion or Case, Sentence or Phrase. A Letter is an indivisible sound, yet not every such sound, but only one which can form part of a group of sounds. For even brutes utter indivisible sounds, none of which I call a letter. The sound I mean may be either a vowel, a semi-vowel, or a mute. A vowel is that which without impact of tongue or lip has an audible sound. A semi-vowel, that which with such impact has an audible sound, as S and R. A mute, that which with such impact has by itself no sound, but joined to a vowel sound becomes audible, as G and D. These are distinguished according to the form assumed by the mouth and the place where they are produced; according as they are aspirated or smooth, long or short; as they are acute, grave, or of an intermediate tone; which inquiry belongs in detail to the writers on metre. A Syllable is a non-significant sound, composed of a mute and a vowel: for GR without A is a syllable, as also with A,--GRA. But the investigation of these differences belongs also to metrical science.