Ah, salt: the tastiest rock we all eat, and for much of history, a far more precious commodity than one might think.
Today, it costs mere pennies for the pound, yet wars have been waged and nations have collapsed over this plain white crystal.
But what made this seemingly simple seasoning so vital and lucrative? Well, for a start, you can't live without it, literally.
Without salt, your muscles would cramp, you'd get dizzy and eventually all your cells would just shut down.
You might think such an essential mineral would be easy to supply: after all, the ocean's full of it.
But, turning seawater into usable salt is a lot harder than it sounds - boiling water famously requires a lot of energy.
You could let the sun do it - and that is indeed one method people have used since ancient times.
But that, of course, only works reliably in hot, sunny climates near the coast, and only if it's not cloudy or raining.
Fortunately, Mother Nature blessed us with another (much more reliable) source of salt: in vast deposits deep underground.
To be a salt miner was a cruel fate - one that the Romans, for example, routinely inflicted upon slaves and criminals.
