This is a story about madness. It can be found in Daniel, chapter 4. King Nebuchadnezzar dreams of a mighty tree which is cut down, leaving only the roots and a stump, which is bound in iron. Daniel interprets the dream to mean that the king is to be cast out for his pride, to live amongst animals for seven years, unless he changes. The experience of being cast out into madness will, however, purify him - the stump will remain, ready to shoot again when he acknowledges 'that Heaven rules'. In the story this is what happens.
I draw great comfort from this story for myself, because it suggests that God will allow madness to intervene to prevent evil taking place, after which there is redemption. Nebuchadnezzar is not a Jew but a foreign king, yet this redemption is available to him.
That's how I read the tale, anyway.