Le Mat is ultimately a teaching about essential freedom. Every other arcanum represents a state, a force, an archetype that can possess us. Le Mat represents the one who walks through all of them without being captured by any. He is the witness, the pilgrim-soul, the consciousness that remembers it is only passing through.
He is the card of the person who has understood that life itself is the path, not the destination — and who has therefore stopped trying to arrive.