They say spilling salt brings bad luck.
Of course they say that.
Sale, from Latin sal, salis, was such a precious resources that the ancient Romans used to pay sodiers with it. That’s why salario, ‘salary’.
Cum grano salis, ‘with/like a grain of salt’ we say, meaning taking something not too literally, but with skepticism. Sal, in Latin also means ‘wit’ or even ‘intelligence’, so cum grano salis means also ‘with a little amount of wit’
Avere sale in zucca literally ‘having salt in one’s head’ means ‘to be smart enough’ in Italian.
The ancient superstition connected with salt just mean “don’t waste it! You idiot!”.
(See also “I miss Italian creative scaramanzia – 1-2″ https://misshome.wordpress.com/2013/11/28/150-i-miss-italian-creative-scaramanzie-1/ https://misshome.wordpress.com/2013/12/03/151-i-miss-italian-creative-scaramanzia-1/ )