"Let us put some pressure now on this word ananke.

Chantraine concludes that 'no etymology grasps that real sense of ananke and its derivations: 'constriction' and at the same time 'kinship.' The underlying notion that might justify this double semantic development would be that of the bond.' Others see the word as being close to the idea of 'taking in one's arms.' When speaking of Heracles caught in the horrendous shirt of Nessus, the chorus in the Trachiniae begin: 'If in the Centaur's murderous net, a dolopoios ananke torments him ...' But how are we to understand dolopoios ananke? A 'deceitful embrace'? Or 'deceitful necessity'? Or both? Once again we have the net, and necessity seen as a lethal embrace. With wonderful monotony, the net, its knots ever ready to tighten, is always there. It falls over Aphrodite's adulterous bed, over the battlefield beneath the walls of Troy, over being itself, and the cosmos, and the blistered body of Heracles. Whatever the situation, that one weapon is more than enough for Ananke. There were many in Greece who doubted the existence of the gods, but none ever expressed a doubt about that net, at once invisible and more powerful than the gods.

When Alexander arrived in Gordium, he went to the acropolis and found the cart that was tied to its yoke with a knot that no one had been able to undo. There was a legend about that cart, 'which said that whoever untied the knot that bound the cart to its yoke would rule over all of Asia. The knot was tied with cornel bark, and it was impossible to find either beginning or end. Unable to untie the knot and not wanting to leave it as it was, in case his failure should spread disquiet through his army, some say that he sliced the knot cleanly with his sword and then claimed that he had untied it.' But there's another version to the story, according to which Alexander 'removed the belaying pin from the drawbar [this was a wooden pin forced into the drawbar and around which the knot was secured] and thus removed the yoke from the drawbar.' Then Alexander and his followers ' went away from the cart convinced that the oracle's predictions about untying the knot had been fulfilled.' Thus, 'the knot that can be neither broken nor loosened, the knot that Zeus and Poseidon tightened around the heads of the warriors beneath the walls of Troy, was not to be untied even by Alexander.

...
In the late pagan era we can still find this in Macrobius: 'amor osculo significatur, necessitas nodo' : 'love is represented with a kiss, necessity with a knot.' Two circular images, the mouth and the noose, embrace everything that is. Eros, 'born when Ananke was lord and everything and everything bowed before her gloomy will,' once boasted that he had gained possession of the 'Ogygian scepter,' primordial as the waters of the Styx itself. He could now force 'his own decrees upon the gods.' But Eros said nothing of Ananke, who had come before him. There is a hostility between Eros and Ananke, a hostility that springs from an obscure likeness, as between the kiss and the knot" (97-99).