For the study of origins, however, we must turn back to the earliest type, Old Comedy, which is entirely unlike any present-day genre. We are fortunate in possessing eleven complete plays of Aristophanes, the chief poet of Old Comedy; and though no two of them are exactly alike in the details of their structure, yet the general outline is clear. The leading features are as follows:[94] 1. The _prologue_ (πρόλογος) spoken by the actors and serving both as an exposition and to set the action of the play in motion. 2. The _parodus_ (πάρoδος), or entrance song of the chorus. Originally this division must have been exclusively choral, but by Aristophanes’ time it has been developed so as sometimes to include lines spoken by actors. 3. The _agon_ (ἀγών, “contest”), a “dramatized debate” or verbal duel between two actors, each supported by a semi-chorus; see p. 43, below. 4. The _parabasis_ (from παραβαίνω, to “come forward”), a “choral agon” in which the chorus, the actors being off stage, march forward to address the audience. When complete, the parabasis consists of seven parts which fall into two groups: the first group contains three single parts, which were probably rendered by the first coryphaeus. Dropping all dramatic illusion and all connection with the preceding events of the play, he sets forth the poet’s views concerning his own merits and claims upon the public, ridicules the rival playwrights, announces his opinions on civic questions, etc. The second group contains four parts in the form of an epirrhematic syzygy, i.e., a _song_ (ᾠδή) and _epirrheme_ (ἐπίῤῥημα, “speech”) by one semi-chorus and its leader, respectively, are counterbalanced by an _antode_ (ἀντῳδή) and an _antepirrheme_ (ἀντεπίῤῥημα) by the other semi-chorus and its leader; here the chorus usually sing in character once more, the knights praising their “horses,” the birds their manner of life as compared with men’s, etc.[95] 5. There follows a series of _episodes_ (ἐπεισόδια), histrionic scenes separated (6) by brief _choral odes_ (στάσιμα or χορικά). The episodes portray the consequences of the victory won in the agon (3). For example, in the _Acharnians_ the subject of controversy is whether Dicaeopolis shall be punished for the alleged treason of having made a private peace with Sparta, and part (5) represents him, in a succession of burlesque scenes, as enjoying the fruits of that peace. 7. The _exodus_ (ἔξοδος), or recessional of the chorus. Properly speaking, this should contain only the final, retiring song of the chorus (the ἐξόδιον), but the term came to include the histrionic passage just preceding it, also. This is a very incomplete sketch of a highly complicated subject, but it will suffice for present purposes.