[RU OX Alum]

most superstitions i think can be explained, for exmaple, friday the 13th is unlucky because if you were a knight templar, or one of their supporters, you would have been burnt at the stake in October, 13something, or some such date. Getting burned alive would count as having bad luck, in my opinion anyway. Also, the thing about mirrors is because people used to believe that the soul of the person stayed in the mirror, so if you broke it, it could take up to seven years for the soul to return, and they get scarred and lost rather easily.

I have no idea why passing someone the salt directly is bad luck (or maybe just bad manners from a different culture)