Why people cry when cut an onion??

The doctors tell that the onion is good for our health, however all we cry when cut an onion.

The answer is that we cry when cut the onion because this to cut their sheets releases a gas called "Allyl Sulfide" that irritate our eyes.

When we cry, the tears prevent that this gas enter to our eyes, keeping our view in good conditions and preventing any damage for our eyes or view.

Magnific!!!