But Aratus, being now for the first time chosen general of the Achaeans ravaged the country of Locris and Calydon, just over against Achaea and then went to assist the Boeotians with ten thousand soldiers, but came not up to them until after the battle near Chaeronea had been fought, in which they were beaten by the Aetolians, with the loss of Aboeocritus the Boeotarch, and a thousand men besides. A year after, being again elected general, he resolved to attempt the capture of the Acro-Corinthus, not so much for the advantage of the Sicyonians or Achaeans, as considering that by expelling the Macedonian garrison he should free all Greece alike from a tyranny which oppressed every part of her. Chares, the Athenian, having the good fortune to get the better, in a certain battle, of the king's generals, wrote to the people of Athens that this victory was "sister to that at Marathon." And so may this action be very safely termed sister to those of Pelopidas the Theban and Thrasybulus the Athenian, in which they slew the tyrants; except, perhaps, it exceed them upon this account, that it was not against natural Grecians, but against a foreign and stranger domination. The Isthmus, rising like a bank between the seas, collects into a single spot and compresses together the whole continent of Greece; and Acro-Corinthus, being a high mountain springing up out of the very middle of what here is Greece, whensoever it is held with a garrison, stands in the way and cuts off all Peloponnesus from intercourse of every kind, free passage of men and arms, and all traffic by sea and land, and makes him lord of all that is master of it. Wherefore the younger Philip did not jest, but said very true, when he called the city of Corinth "the fetters of Greece." So that this post was always much contended for, especially by the kings and tyrants; and so vehemently was it longed for by Antigonus, that his passion for it came little short of that of frantic love; he was continually occupied with devising how to take it by surprise from those that were then masters of it, since he despaired to do it by open force.
Therefore Alexander, who held the place, being dead, poisoned by him, as is reported, and his wife Nicaea succeeding in the government and the possession of Acro-Corinthus, he immediately made use of his son, Demetrius, and, giving her pleasing hopes of a royal marriage and of a happy life with a youth, whom a woman now growing old might well find agreeable, with this lure of his son he succeeded in taking her; but the place itself she did not deliver up, but continued to hold it with a very strong garrison, of which he seeming to take no notice, celebrated the wedding in Corinth, entertaining them with shows and banquets every day, as one that had nothing else in his mind but to give himself up for a while to indulgence in pleasure and mirth. But when the moment came, and Amoebeus began to sing in the theatre, he waited himself upon Nicaea to the play, she being carried in a royally decorated chair, extremely pleased with her new honour, not dreaming of what was intended. As soon, therefore, as they were come to the turning which led up to the citadel, he desired her to go on before him to the theatre, but for himself, bidding farewell to the music, farewell to the wedding, he went on faster than one would have thought his age would have admitted to the Acro-Corinthus, and, finding the gate shut, knocked with his staff, commanding them to open, which they within, being amazed, did. And having thus made himself master of the place, he could not contain himself for joy; but, though an old man, and one that had seen so many turns of fortune, he must needs revel it in the open streets and the midst of the market-place, crowned with garlands and attended with flute-women, inviting everybody he met to partake in his festivity. So much more does joy without discretion transport and agitate the mind than either fear or sorrow.
Antigonus, therefore, having in this manner possessed himself of Acro-Corinthus, put a garrison into it of those he trusted most, making Persaeus the philosopher governor.
Now Aratus, even in the lifetime of Alexander, had made an attempt, but, a confederacy being made between Alexander and the Achaeans, he desisted. But now he started afresh, with a new plan of effecting the thing, which was this: there were in Corinth four brothers, Syrians born, one of whom, called Diocles, served as a soldier in the garrison, but the three others, having stolen some gold of the king's, came to Sicyon, to one Aegias, a banker, whom Aratus made use of in his business. To him they immediately sold part of their gold, and the rest, one of them, called Erginus, coming often thither, exchanged by parcels. Becoming, by this means, familiarly acquainted with Aegias, and being by him led into discourses concerning the fortress, he told him that in going up to his brother he had observed, in the face of the rock, a side cleft, leading to that part of the wall of the castle which was lower than the rest.
At which Aegias joking with him and saying, "So, you wise man, for the sake of a little gold you have broken into the king's treasure; when you might, if you chose, get money in abundance for a single hour's work, burglary, you know, and treason being punished with the same death." Erginus laughed and told him then, he would break the thing to Diocles (for he did not altogether trust his other brothers), and, returning within a few days, he bargained to conduct Aratus to that part of the wall where it was no more than fifteen feet high, and to do what else should be necessary, together with his brother Diocles.
Aratus, therefore, agreed to give them sixty talents if he succeeded, but if he failed in his enterprise, and yet he and they came off safe, then he would give each of them a house and a talent.