Gordian knot

The Gordian Knot is a legend of associated with Alexander the Great. It is often used as a metaphor for a problem which has no easy or obvious solution.
Myth story.
In Phrygia (modern Turkey), there was a legendary prophesy about a unique knot which could only be loosened by the man who would rule all of Asia. It was called the "Gordian" knot because it was preserved in Gordium. It supposed to have been created by a man named Gordius.
The knot was complex and tangled. This mythical knot was tied around the part of a wooden cart or wagon.
According to traditional version of the story, Alexander the Great cut the knot with his sword.
In another version of the story, Alexander took away the wooden part which was at the center of the knot; and in this way, the knot was undone.
Alexander solved the problem in a way no one had expected. Then he went on to lead Greek armies which conquered much of the known world.
Meaning.
Today the phrase implies "make it happen" or "get things done".
"Cutting the Gordian knot" has come to mean resolving a difficult problem with one forceful action.
It may mean a problem that has no solution.