Talk:Basilisk/@comment-28484169-20180626033534/@comment-29602226-20180626165741

Actually, in the real world, some people theorized during the Late Middle Ages and Renaissance that some living beings could generate invisible "poisonous light" and shoot it through their eyes, like some sort of "death rays".

It was basically a way to try to "scientifically" prove the existence of witchcraft. The theory went like this: Some people who felt a lot of envy, jealously, anger and hate had their "humors" unbalanced, and their bodies started to produce "extremely subtle venom". The skin prevented that venom from escaping the body, but it could leave it through the eyes, which were "skinless". When the afflicted person was in front of the object of their hate/envy/anger, the production of venom peaked, and it squirted forming jets through the eyes precisely when the afflicted was laying their sight on the object of their envy or hate. The poisonous, invisible jets of light-like venon hit the victim, who got sick...

Gaspar de Ribero, a doctor from the court of king  João III of Portugal (XVI century) supported that theory.