And He was transfigured before them; and His face shone like the sun, and His garments became as white as light.– Matthew 17:2
First, His face shone like the sun. The sun is God himself, and the expression of the glory of who God really is. Second, His clothes became as white as the light, not just testifying of the highest humanity with no spot or wrinkle in His walk with God, but expressing a purity just as God is pure. Usually, we say “His garment is white” means it is pure. But here, it is more than white. No whiteness can express this kind of whiteness. So here it is an expression of purity, just as God is pure.