Salt is a magical substance. It reduces bitterness, enhances sweetness, boosts flavor, and preserves perishable foods. Without it, we would die: the human body can't make sodium, but our nerves and muscles don't work without it. It was considered rare until quite recently, so it's hardly surprising that, throughout history, salt has been the engine behind empires and revolutions. Today, there's a new battle in the salt wars, between those who think that we eat too much of it and it's killing us—and those who think most of us are just fine. Join us for a serving of salt, seasoned with science, history, and a little politics.