Like Iron

Explaining that the earthen body of man, like iron of fine substance, is capable of becoming a mirror, so that therein even in this world Paradise and Hell and the Resurrection et cetera are shown by immediate vision, not in the mode of phantasy.
Then, though thou art dark-bodied like iron, make a practice of polishing, polishing, polishing, That thy heart may become a mirror full of images, (with) a lovely silverbreasted (form reflected) therein on every side.

The Masnawi - Volume 4, 2470