Ever wandered alone on the streets at the dead of night? Well, if you encounter a wizened figure in tattered robes and a hood, and you just can't seem to make out his face no matter which way you look at it, pay your respects. This man is infact Death himself. He only appears to sole travellers at the stroke of 3:33am, so most go their entire lives without ever seeing him "in the flesh", so to speak.
If you're brave enough to speak to him, he may take out an hourglass from his robe. The hourglass represents how much longer you have left to live. If there is plenty of sand in the upper glass, it means you still have a long time left to go before inevitability claims you. But if he takes out an hourglass that contains black flowing sand, then run as fast and as far as you can to the one you love before he finds you. And he will find you.
The black sand represents borrowed time.