Arrian, Anabasis 2.3
When Alexander arrived at Gordium, he was seized with an ardent desire to go up into the citadel, which contained the palace of Gordius and his son Midas. He was also desirous of seeing the wagon of Gordius and the cord of the yoke of this wagon.
There was a great deal of talk about this wagon among the neighbouring population. It was said that Gordius was a poor man among the ancient Phrygians, who had a small piece of land to till, and two yoke of oxen. He used one of these in ploughing and the other to draw the wagon. On one occasion, while he was ploughing, an eagle settled upon the yoke, and remained sitting there until the time came for unyoking the oxen. Being alarmed at the sight, he went to the Telmissian soothsayers to consult them about the sign from the deity; for the Telmissians were skilful in interpreting the meaning of Divine manifestations, and the power of divination has been bestowed not only upon the men, but also upon their wives and children from generation to generation. When Gordius was driving his wagon near a certain village of the Telmissians, he met a maiden fetching water from the spring, and to her he related how the sign of the eagle had appeared to him. As she herself was of the prophetic race, she instructed him to return to the very spot and offer sacrifice to Zeus the king. Gordius reqtiested her to accompany him and direct him how to perform the sacrifice. He offered the sacrifice in the way the girl suggested, and afterwards married her. A son was born to them named Midas. When Midas was grown to be a man, handsome and valiant, the Phrygians were harassed by civil discord, and consulting the oracle, they were told that a wagon would bring them a king, who would put an end to their discord. While they were still deliberating about this very matter, Midas arrived with his father and mother, and stopped near the assembly, wagon and all. They, comparing the oracular response with this occurrence, decided that this was the person whom the god told them the wagon would bring. They therefore appointed Midas king; and he, putting an end to their discord, dedicated his father’s wagon in the citadel as a thank-offering to Zeus the king for sending the eagle. In addition to this the following saying was current concerning the wagon, that whosoever could loosen the cord of the yoke of this wagon, was destined to gain the rule of Asia. The cord was made of cornel bark, and neither end nor beginning to it could be seen.
It is said by some that when Alexander could find out no way to loosen the cord and yet was unwilling to allow it to remain unloosened, lest this should exercise some disturbing influence upon the multitude, he struck it with his sword and cutting it through, said that it had been loosened. But Aristobulus says that he pulled out the pin of the wagon-pole, which was a wooden peg driven right through it, holding the cord together. Having done this, he drew out the yoke from the wagon-pole. How Alexander performed the feat in connection with this cord, I cannot affirm with confidence. At any rate both he and his troops departed from the wagon as if the oracular prediction concerning the loosening of the cord had been fulfilled. Moreover, that very night, the thunder and lightning were signs of its fulfilment; and for this reason Alexander offered sacrifice on the following day to the gods who had revealed the signs and the way to loosen the cord.