Finally we encounter the last two plays in Aristophanes’ surviving body of works. I’ve chosen to group these two together because both have prominent references to Greek tragedians and literature in general. We have already seen several instances of reference to Euripedes, for example in The Acharnians, where the playwright is enlisted to help the main protagonist make a speech on peace. Here, however, past playwrights are more than just referenced: they become the main subject of the plays.

The Thesmophorizae

The plot of Thesmophorizae (Women Celebrating the Festival of Thesmophoria) bears some resemblance to Ecclesiazusae and Lysistrata, in that it also features women convening and planning together. But in contrast to the latter plays, here the focus is not on a women protagonist like Praxagora or Lysistrata, but on the planned object of the women’s wrath: the poet Euripedes, who is fearful that the women will kill him for insulting them through his tragedies. Perhaps the women are displeased with Euripedean tragedies with a woman as the main protagonist such as Hecuba and Medea, both of which end with the heroine successfully plotting and carrying out revenge through brutal murders. However, the complaint seems to run deeper than just that, as eloquently expressed by the First Woman:

FIRST WOMAN
…But I have long been pained to see us women insulted by
this Euripides, this son of the green-stuff woman, who loads us with every kind of indignity. Has he not hit us enough, calumniated us sufficiently, wherever there are spectators, tragedians, and a chorus? Does he not style us adulterous, lecherous, bibulous, treacherous, and garrulous? Does he not repeat that we are all vice, that we are the curse of our husbands? So that, directly they come back from the theater, they look at us doubtfully and go searching every nook, fearing there may be some hidden lover. We can do nothing as we used to, so many are the false ideas which he has instilled into our husbands. Is a woman weaving a garland for herself? It’s because she is in love. Does she let some vase drop while going or returning to the house? Her husband asks her in whose honor she has broken it: “It can only be for that Corinthian stranger.” Is a maiden unwell? Straightway her brother says, “That is a colour that does not please me.” And if a childless woman
wishes to substitute one, the deceit can no longer be a secret, for the neighbors will insist on being present at her delivery. Formerly the old men married young girls, but they have been so calumniated that none think of them now, thanks to
that line of his: “A woman is the tyrant of the old man who marries her.” Again, it is because of Euripides that we are incessantly watched, that we are shut up behind bolts and bars, and that dogs are kept to frighten off the adulterers.

Notice that all the complaints of the First Woman are focused on those which that threaten to undermine the “proper” position of women in the home and family – women are thought to be adulterous and tyrannical, though not murderous, despite that arguably women in Euripedes’ plays display much more the latter behavior than the former. Even in the case of murder, many of Euripedes plays involve women committing their violent actions because they are directly motivated by familial relationships: Electra murdering her mother for killing her father and Hecuba murdering Polymester for killing her son Polydorus. In contrast, in Alcestis a woman is the looming, larger-than-life heroine, as is the case in The Heraclidae (Macaria sacrificing herself to save the others). Only a few plays portray a female character in a thoroughly negative light – perhaps Medea, but Medea is motivated by her husband’s betrayal of her. Only Phaedra in Hippolytus fits the bill as an adulterous and murderous woman. But perhaps Euripedes’ tragedies can be seen as arguing for any sort of female agency and independence, and adultery was a much more realistic possibility in non-fictitious society than murder. At the same time, by putting the complaint into the mouth of a woman who is part of an assembly of women acting like men do in a Greek democratic assembly, Aristophanes achieves a double layer of irony and parody.
The plot of the play involves Euripedes enlisting his father-in-law Mnesilochus to disguise himself as a woman (a reversal of the women’s disguises in Ecclesiazusae), sneak into the assembly during the Thesmophoria and convince them to drop the charge against Euripedes. Mnesilochus’ disguised speech to attempt to sway the assembly emphasize on pushing the women to admit that much of what Euripedes has said about them is true: women do commit adultery and are dishonest. The women (especially the First Woman) are furious at this suggestion and Mnesilochus is quickly found out and exposed. Next, in a passage of dark humor clearly channeling the Greek tragedians, Mnesilochus grabs the baby of the First Woman and threatens to kill it unless they release him. But he finds out that the baby is really just a wine skin, proving him right – that the First Woman is more of an alcoholic than a mother.
At the end, Euripedes negotiates a deal that he would refrain from further painting the women in a bad light in his future plays, and by trickery he manages to release Mnesilochus too. Looking at the play as a whole, it again shows Aristophanes’ conservative sympathies, which can only be described as cunning – the initial humorous double irony of a democratic assembly of women complaining about their “progressive” depictions in Euripedes’ plays is transformed into a straight-up exposure of women as emotional and hypocritical beings.

The Frogs

In The Frogs, the central feature is a commentary on the nature of literature itself. As such, it provides us with a great opportunity to reflect on the nature of all the Greek imaginative literature that we have read so far. The commentary takes the form of a literary competition between Aeschylus and Euripedes to decide who is the best poet in the underworld, judged by Dionysus. Each come up with creative insults to each other, such as Aeschylus arguing that the debate wasn’t fair, because “My poetry survived me, while his [Euripedes’] died with him://He’s got it here, all handy to recite.” Euripedes criticizes Aeschylus’ works as having minimalist language and confusing, bombastic imagery:

EURIPIDES
‘Twas all Scamanders, moated camps,
and griffin-eagles flashing
In burnished copper on the shields,
chivalric-precipice-high
Expressions, hard to comprehend.

He argues that his own plays focused on ordinary people who try to reason about their actions:

EURIPIDES
I taught them all these knowing ways
By chopping logic in my plays,
And making all my speakers try
To reason out the How and Why.

Aeschylus criticizes Euripedes in a more predictable way: he accuses him of subverting human nature (all his characters seem to be evil and flawed in some way) and depicting indecent actions such as murder, incest, and adultery. Instead of being unrealistic and bombastic, the abundance of heroic imagery is meant to expose only good things to the people, motivating them to measuring themselves against the same:

AESCHYLUS
But others, many and brave, he taught,
of whom was Lamachus, hero true;
And thence my spirit the impress took,
and many a lion-heart chief I drew,
Patrocluses, Teucers, illustrious names;
for I fain the citizen-folk would spur
To stretch themselves to their measure and height,
whenever the trumpet of war they hear.
But Phaedras and Stheneboeas? No!
no harlotry business deformed my plays.
And none can say that ever I drew
a love-sick woman in all my days.

In short, the debate between Aeschylus and Euripedes is between old and new, conservative idealism and modern realism. We like to think of classical art and literature as being idealistic, depicting mainly heroes, gods, and larger-than-life figures. Realism is an innovation mainly of the last 150 years, at most. Even Euripedes is not exempt from this: the characters in his plays are mostly still prominent, heroic figures (Hecuba, Andromache, Electra, Alcestis, and so on). That being said, there are notable breaks from this pattern, such as Hippolytus, Ion, and the prominent parts given to Electra’s peasant husband in his version of the story. Still, Euripedes doesn’t shy from showing his heroes and noblemen submit to their basest desires or perish due to the actions of others. As put in his own words, he believes his plays exhibit a more coherent logic in that way.
This reminds me of several common debates about the “super-realist” predominant fantasy story of today, George R.R. Martin’s A Song of Ice and Fire, or its television series adaptation Game of Thrones. Multiple prominent characters, including virtuous and heroic ones are brutally killed in the series. Depictions of sexual violence abound. All of this has been defended by the author as being necessary to depict realism in war. Most people who fight are indeed not heroes who rise against all odds and save the day. Most perish pointlessly in the conflict. But the more traditionalist reply is that we do not read stories for the sake of pure realism. If we wanted to then we would read non-fiction or news stories. Instead, fiction is meant to be read to entertain and inspire, and so only good things must be shown. Augustine had a similar view about the bad influence of theater and drama in his Confessions, as is Plato in The Republic. 
After these abstract arguments about the nature of their literature, the two tragedians continue by reciting lines from their plays. Famously, when Euripedes starts reciting his prologues, Aeschylus vows to “smash your prologues with a bottle of oil.” He proceeds to interrupt Euripedes’ verse with the phrase “Lost his bottle of oil” several times. Interestingly, the phrase kind of “fits” in the different passages that are recited. This highlights Aeschylus’ preference for simpler language (but more elaborate subject matter and characters). Euripedes mocks this: he recites several lines from different Aeschylus choruses which end with the same line: “Approachest thou not to the rescue?” Next, the words of the two poets are “weighed”: Aeschylus wins because his imagery features heavier objects than Euripedes’. But Dionysus still cannot decide conclusively on the overall winner. At the end, the winner is decided by who can give the best advice to save the city. Euripedes goes first, but his advice is too flowery to be comprehensible. Thus Aeschylus wins the day.
The final closing lines of the play unambiguously reveal Aristophanes’ preference for Aeschylus. The chorus laments poets who strip tragedy of the noble and the good. The god Pluto celebrates Aeschylus as a real savior through his noble thoughts:

PLUTO
Farewell then Aeschylus, great and wise,
Go, save our state by the maxims rare
Of thy noble thought; and the fools chastise,
For many a fool dwells there.

In other words, Aeschylus’ literary victory in the underworld was not merely for humorous effect, but likely a real literary commentary. By favoring him, and having lampooned Euripedes in Thesmophorizae and Peace, Aristophanes’ distaste for progressive, realist literature is as real as anything. But we must remember the great irony: his comedies, as we have seen, feature many things which would never be considered “good” and “noble”: plenty of references to defecation, genitals, sex, and slapstick violence. Is anything in Euripedes really “worse” than the open lewdness of the women of Lysistrata? In addition, none of the lewd female characters in Aristophanes get their comeuppance, unlike Euripedes’ tragedies. Perhaps Aristophanes’ objections are only to tragedy as a specific art form, not drama in general: maybe he thinks that nobody would take comedy seriously as a model of moral virtue, but tragedy is perceived to be meaning to teach us something. All in all, I think that it would not be fair to view Aristophanes’ comedy primarily as vehicles for conservative propaganda. Instead, we must celebrate his mastery of the art of double irony, double parody, double meaning: the Mozartian ability to combine the high and low arts, the slapstick and crude with serious commentary on war and society. That is his contribution to the Great Conversation.