Onions cells contain small amounts of propanethiol S-oxide. When you cut one open, this compound mixes with enzymes that release a sulfur compound which is itself not noxious. However, when it encounters the water in our tear ducts, it creates sulfuric acid which is a strong irritant. Rubbing ones eyes will only make things worse if some of the compound has adhered to the skin while cutting the onion.

Some people have noticed that running cold water on your wrists prior to cutting an onion can reduce the irritation. The explanation for this is related to putting cold keys on your back to reduce a nosebleed. The cold sensation makes blood vessels in the nasal passages constrict. The route to the tear glands is through the nose and constriction of the blood vessels may slow this process down.

Onions make you cry because they remind you that your own identity, your "self," is as ill-defined as the core of an onion. In a quest to slay inferior selves in order to perfect our own lives and come out as our own ideal person, are we simply peeling back layers of onion, searching for a core? The core, you see, is naught but more small layers - or, perhaps, a point from which concentric layers begin to radiate. Decide for yourself where its boundaries lie.

Henrik Ibsen's Peer Gynt makes extraordinary effort to stay true to himself. When the fellow finds himself starving in the forest, he digs up a wild onion and begins to peel back its layers. Each one, he remarks, is a different stage of himself throughout the play. Where is the core, the thing he's been seeking through the entire story?

I could say that it's not there. I would rather say that it's there, and up to us to define.

No onion ever made me cry as much as the budding vidalia I found with two cores.