"What then shall I compare it to?"
The kingdom is not the treasure. Because it is more than the treasure. The kingdom is not the treasure in the field. Because it is more than the treasure in the field. The kingdom is the man who finds the treasure in the field. It is the man of joy. It is a man and his joy of finding what was always there, only hidden, and thus lost to him. The kingdom of God is him stumbling upon the unfindable and unreproducible joy of finding what was lost. It is his upturned face in joy of discovery. Or more accurately: joy of re-discovery. The Kingdom of God is him leaping in an eternal celebration of finding. Just as the kingdom of Hell was him lying in an unmarked grave of losing: a scattering, a fractured and isolated senility of losing. Hell is filled only with man in unmarked graves.
What is greater than the treasure? The man who finds it.
Finding a thing (or losing a thing, for that matter) is, by orders of magnitude, greater than the thing itself. Because then it exists. But when it is in a state other than being lost or being found, it does not exist. It is forgotten. It slips back into a place below our consciousness, outside our awareness. Recedes back to The Sheol beneath our eyes. Hell is down there. Yet a doorway to heaven too. Either we never knew it existed and so couldn’t be lost or found, or we once knew it existed but forgot until it was lost or found.