I wonder...
A very curious light haired boy leaned over from his bed and reached into the drawer of the table beside it; he pulled out a strange purple instrument with a printed eye on its single red lens. He leaned over slowly, hovering the object a few inches above head of the boy who was sleeping heavily in the bed besides him.
He positioned it above the mage's head; for a few seconds, all he could see was, while a bit shocking in itself, was Vaati's brain matter; but he stared for a few seconds more, knowing what the Lens of Truth was capable of.
He watched as a small projection of the inner workings of Vaati's mind begin to leak from his head underneath the Lens of Truth and wisp around the room. At first, all of the light in the room was sucked away, and there was only a black atmosphere with a slit of red - but soon, the slit blossomed, until Link indentified it as a sun. A rising sun.
"...He overcame his darkness," Link whispered in awe. "He is filling himself with light."
A/N: For any of you wondering why Link used the Lens of Truth to look into Vaati's mind and not his heart, it was said Vaati learned of the darkness in the hearts of men; I think this corrupted more how he interpreted the world, which led to him becoming very bitter and power crazy, rather than him just being truly evil.
Also, the brain is what stores emotions and concepts, and while the heart is more symbolic, I found it a tad less accurate. But that's just my take on it.