Derma Sciences sells a wound bandage called Medihoney that hospitals use to treat burns and slow-healing sores. The active ingredient is exactly what you'd guess: honey. The same stuff in your pantry pulls water out of damaged tissue and releases trace amounts of hydrogen peroxide, which is why archeologists keep finding pots of it in Egyptian tombs that are still perfectly safe to eat after 3,000 years.
Three things keep honey from spoiling, according to a Smithsonian Magazine piece by Natasha Geiling. The first is moisture, or the lack of it. Honey is essentially sugar, and sugar is hygroscopic, meaning it grabs moisture from anything around it. Untouched honey contains almost no water of its own. "Very few bacteria or microorganisms can survive in an environment like that," Amina Harris of the Honey and Pollination Center at UC Davis told Smithsonian. Nothing alive can hold onto its water in there.
The second is acidity. Honey's pH ranges from 3 to 4.5, high enough to kill most things that would want to grow in it. Molasses is also hygroscopic and acidic, with a pH around 5.5, and it eventually spoils.
The third factor comes from the bees themselves. Nectar starts out 60 to 80 percent water. Bees flap their wings over the comb to physically dry it down, and a stomach enzyme called glucose oxidase converts the regurgitated nectar into gluconic acid and small amounts of hydrogen peroxide. That last bit is what makes honey medicinal. Sumerians wrote honey into roughly a third of the prescriptions they pressed onto clay tablets, and Egyptian doctors slathered it on skin and used it for eye ailments.
The seal on the jar is the last variable. Open honey in a humid kitchen will absorb water from the air and eventually go off. The tomb honey survived because somebody put a lid on it.
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