Somewhere in a museum sits a pot of honey older than most empires, and it is, technically speaking, still breakfast. Archaeologists exploring ancient Egyptian tombs have found honey thousands of years old and perfectly edible.

The trick is patient chemistry. Honey is mostly sugar and hardly any water, so thirsty microbes shrivel before they can settle in. It is gently acidic, too, and the bees add a touch of an enzyme that produces tiny amounts of hydrogen peroxide. A pantry, a fortress, and a chemistry set, all in one jar.

The bees solved food preservation several thousand years before we invented the refrigerator.

So the jar at the back of your cupboard that has gone stiff and crystally is not ruined. It is just resting. Warm it slowly, stir it kindly, and it remembers exactly what it was.