Classic question... Classic answer from the Chef in the movie The Cook, the Thief, His Wife & Her Lover
[Georgina] "When you make out a menu, how do you price each dish?
[Richard Borst, "The Cook"] I charge a lot for anything black... Grapes, olives, blackcurrants.
People like to remind themselves of death, eating black food is like consuming death, like saying, "Death, I'm eating you."
Black truffles are the most expensive. And caviar. Death and birth. The end and the beginning.
[Richard Borst, "The Cook"] We also charge for vanity.