 And over the centuries, have we changed the types of salt that we value the most? That's a really interesting question, because initially, usually it's the thing that you can't have that's the thing you value, like white bread was the thing that people valued, and also white salt was the thing that people valued. Pure, fine-flowing, free-flowing salt, the stuff you get in a kind of plastic bottle now and costs 30p or whatever it is from the supermarket.