For the archon also allowed the comedian a chorus at some late date but they were volunteers. And writers mention crafters (poets) of it (comedy) at the point when this (comedy) already possessed some forms,  but who assigned it masks or prologues or a number of actors and any element it has  is unknown.
But crafting stories  in the beginning came from
Epic poetry is consistent with tragedy up to the point that it was an imitation by speech with meter of men of substance ; but they differ in this respect: by (epic) having the single meter and being narrative, and, morever, in regards to length: on the one hand tragedy especially because it attempts to be under the period of one day or to exceed it just a bit, but epic poetry is without boundary in time and in this respect it differs though at first this was done  similarly in tragedies and epics. But in regards to the sections, some of these are (similar) and some particular to tragedy.
Because whoever knows about weighty or trivial tragedy also knows about epics, for the things which epic poetry has belong to tragedy; but the things which tragedy has are not all in epic poetry.
6. We will speak about the mimetic art in hexameter and about the comedic art later.
But concerning tragedy, examining it from the things said so far let us speak about what became the extent of its essence: tragedy, then, is an imitation: of a virtuous action possessing magnanimity in its completion; by means of language sweetened seperately by each of the forms in the parts; and of the men accomplishing the thing, effecting the dissolution of such experiences  not through narative (but) through mercy and pity.
With respect to “sweetened language” I mean (language) that has rhythm and harmony and tune; by “the forms separately” I mean that only some things are effected through meter and again other things through song.
And since those men who act craft the imitation, first then, by necessity, some part of tragedy  would be the beauty of appearance, then poetic song and diction; for by means of these they craft the imitation.
With respect to “diction” I mean the arrangement of metres, and with respect to “poetic song” the whole apparent sense which it has.
But when the imitation is of an action, and is acted by some people acting, who necessarily are some certain sorts (of people) according to both character and thought—for we say that through these things actions are whatever sorts that they are, and it is by nature that  the two causes of actions are thought and character, and people all both hit and miss the mark in respect to these things—indeed the story is the imitation of the action.
[[Note to Burglar: I went past my allotted section but could not find a decent breaking off point—editing of the post is welcome]]
 Archon (Plural: Archontes) from the OCD: “In Athens by the 6th century there were nine annually appointed archons … in the bth century BC the archons and in particular the one entitled archon were the most important officials of the Athenian state … in the later 5th and 4th century BC the archons’ duties were particularly religious and judicial … the archon was responsible for a number of religious festivals …”
 An awkward sentence to translate literally: the meaning is that by the time we hear about comedians the comedic form already had its basic elements.
 Greek is the idiom: “hosa toiouta”
 Staying consistent with Burglar: the Greek word is “mythos” ie., myth, which is a problematic concept to translate into English.
 mechri + gen = measure or degree: “in so far as; up to the point that”; end of sentence the text has been significantly disputed, I followed R. Kassel, Oxford, 1965: “mechri men tou meta metrou logwi mimesis” because it was the only rendition that made sense to me—which does not necessarily imply it is the correct rendition! Also, I think I have translated “spoudaios” differently every time: here “men of substance” a few sentences down “weighty tragedy”.
 katharsis twn toioutwn pathematwn. Because Aristotle’s “catharsis” is one of the few ideas from the Classical period that you can mention at a party and not get sent home early, in addition to the above context I offer the reader a summarized dictionary entry for the word:
I. cleansing from guilt or defilement, purification [sense used in Christian texts]; cleansing of the universe by fire, [Zeno and Chrysippus]; cleansing of food by or before cooking.
II. clarification [Epicurus]
III. Medical: clearing off of morbid humours, etc., evacuation, whether natural or by the use of medicines [cf. Galen.17(2).358]; purification of the menses in women, [Hp.Aph.5.60]. Aristotle’s use is understood under this category:
a. τραγῳδία . . δι᾽ ἐλέου καὶ φόβου περαίνουσα τὴν τῶν τοιούτων παθημάτων καθαρ. Aristotle, Poetics1449b28; see also Politics 1341b38.
IV. pruning of trees.
V. winnowing of grain.
VI. clearing of land.
 I understand Aristotle to be still discussing tragedy’s essence.
 LSJ: phuw: B.II.1: “the pf. and aor. 2 take a pres. sense, to be so and so by nature”