This is a very old story. A sage was sitting on the bank of a river. Just then, an eagle flew past carrying a tiny mouse in its talons. The sage used his spiritual power to transform the mouse into a beautiful little girl. He raised her as his own daughter.
When she grew up, the sage thought — 'I must find the very best husband for her.' He began with the Sun god. 'Are you a worthy match for her?' he asked.
The Sun replied, 'I am full of blazing light. But the clouds cover me — they are greater than I am.' So the sage called on the clouds.
The clouds said, 'I can cover everything. But the wind blows me away — the wind is greater than I am.' So the sage called on the wind.
The wind said, 'I can blow everything away. But the mountain does not move for me — the mountain is greater than I am.' So the sage called on the mountain.
The mountain said, 'I stand firm and immovable. But a mouse burrows right through me — the mouse is greater than I am.'
The sage asked the girl what she thought. She looked at the mouse. Her heart was at ease. The sage transformed her back into a mouse. The two of them went away together.
Whatever is in one's nature, that is where true happiness lives. Changing the outer form does not change the nature within.