From Gilbert Murray (the translator's) forward to Oedipus at Colonus--very interesting, as they say--

Greek tradition tells us that the play was produced by the poet's grandson, Sophocles the younger, four [Pg 6] years after the author's death at the age of ninety. This is confirmed by the metrical and linguistic tests, which clearly prove the Colonêüs to be among the last of the poet's writings; indeed it would almost seem that some parts of the play required a fourth actor, unless we escape that startling conclusion by the somewhat evasive hypothesis of a supernumerary persona muta who was not always entirely mute.[2] The play certainly leaves the impression of coming from one who has largely left the turmoil of life behind him and looks back upon it with deepened understanding and mature mastery of language and poetry.

Some modern readers have seen signs of old age in a certain lengthiness and lack of concentration in the drama. It is, as Aristotle would say, "episodic," and each episode involves some dissipation of interest. The ancient critics, however, seem to have singled out the "oeconomia"—the construction or management—of the play for particular admiration. Aristophanes of Byzantium considered that in this respect it had no equal. He might have pointed out that it contains many characters, none of them mere vessels of rhetoric but each with his own ethos and his own purposes and a good reason for entering when he does. And it is true that each episode serves its purpose in showing the gradual sanctification or "heroization" of Oedipus. A hero was by no means necessarily a lovable character; he had to be firstly, uncanny and different from common men, and secondly formidable, with powers to injure[Pg 7] or to bless, connected always with a taboo grave. So far he is like a mediaeval saint; but he need not be saintly in character. Aegisthus and Salmoneus, famous for their sins, were "heroes." An extreme case is that of the athlete Cleomêdês, who, after killing his opponent, went mad and destroyed a school with sixty children in it; naturally people were afraid of such a being and felt it desirable to "appease" his tomb. The terrific cursing of Polynices by his father, which was heart-breaking to Antigone, seems to us a very strange prelude to the scene of something like sanctification which immediately follows, but of course heroization is not the same thing as sanctification. The curse showed how truly formidable the inmate of that mysterious tomb was to be; and we must always remember that in an insecure and unpoliced society, like those of antiquity in general, the punishment of the wicked was a keenly felt social necessity. Was the wrong-doer to go scot-free, and the cry of the "wronged ones in the darkness" to be left unheard? A true hero must curse as well as bless.

https://gutenberg.ca/ebooks/murraysophocles-oedipusatcolonus/murraysophocles-oedipusatcolonus-00-h.html