Francisci Porti Cretensis... In omnes Sophoclis tragoedias prolegomena, ut vulgo vocantur

they are, says Aristotle. Nevertheless, the Tragedians once used the tetrameter, according to the same Aristotle in Rhetoric book 3; then, having abandoned the tetrameter, they followed the iambic. The words of Aristotle are these: "Those who composed tragedies first used the tetrameters, then they transitioned to the iambic."

Horace:

Rage armed Archilochus with his own iambic.
The sock adopted this foot, as did the grand buskins:
Apt for alternating conversations, and conquering
The noise of the crowds, and born for acting out things.

Cicero says the iambic measure falls into an apt oratorical style because it is most similar to speech; and so it happens that it is used in plays primarily because of the similarity to reality, whereas the dactylic measure of hexameters is better accommodated to grandiloquence.

Now we must come to the argument of the play, where the difference between Euripides and Sophocles must first be declared.

This must be demonstrated in a few words, so that judgment concerning both may be easier.

Euripides is more submissive and more accommodating to popular ears, and approaches the oratorical genre more closely, so that he seems to those who are preparing themselves for action to be much more useful than Sophocles; he is dense with aphorisms, filled with commonplaces, and most weighty in arguments on both sides. In moving the affections, he is, by the judgment of all tragedians of Aristotle, tragikotatos most tragic, that is, the most apt for moving the affections. Virgil, 8th Eclogue:

Your songs alone are worthy of the Sophoclean buskin.

But Sophocles is always grave, always tragic, always sublime, and grandiloquent; yet in such a way that he tempers gravity with pleasantness, infuses tragic severity with poetic sweetness, and since those two things primarily constitute tragedy—oitos pity and thauma wonder—one cannot easily judge whether he moves one more by delight or by wonder and pity. Finally, he is the greatest poet, and always breathes Homer, the prince of all poets. For he imitates him above all, from whom every genre of poetry took its origin. Therefore, Plato wrote that he was the "father of tragedy."