"An impossible interlocking shape that can only exist in two dimensional space"
The Gordian Knot is an Ancient Greek legend of Phrygian Gordium associated with Alexander the Great who is said to have cut the knot in 333 BC. It is often used as a metaphor for an intractable problem (untying an impossibly tangled knot) solved easily by finding an approach to the problem that renders the perceived constraints of the problem moot ("cutting the Gordian knot").