Belief in the Evil Eye is something that crosses over many Cultures on this Planet, among which are the Australian Aborigines, Jews, and all over Europe and the New World. In Hebrew it is “ayin ha'ra”, Italian “il mal’occhio”, the same as in English. This Belief seems to be based on the idea that somehow, illness and misfortune can be brought about by a stare from someone with that Power, often without intention, possibly by someone who is envious, jealous, or covetous. Hence, in English, it is also sometimes called the “envious eye”. In Yiddish, there exists the curious expression “kinnahora” (“let it be without the Evil Eye”), from Hebrew “Kein ayin ha’ra”, a word often uttered when mentioning someone else’s success, to insure that no harm comes to them, meaning “I do not intend my praise to suggest that somebody might be enviously casting the Evil Eye”. This is often said along with “Mazel Tov” (“good star”), which means “Congratulations”.
An example might be, “Your daughter is getting married? Mazel Tov! Kinnahora!”
Originally, in the Mishnah, the expression "Evil Eye" simply denoted that its possessor could not handle others’ good fortune. In this sense the term is used in contrast to the "good eye," the possessor of which enjoys seeing others’ success.
Later, in the Babylonian Talmud, the Idea developed that some persons do have the kind of Power mentioned above, and there are a number of methods to ward off the harmful effects of the Evil Eye. A still-popular custom is spitting on the ground three times.
A belief that the descendants of the biblical Joseph were immune from the effects of the Evil Eye lead to a curious incantation found in the Talmud to ward off the effects: "Take the thumb of the right hand in the left hand and the thumb of the left hand in the right hand, and say: "I am of the seed of Joseph, over whom the Evil Eye has no Power.'"
Maimonides felt that the Evil Eye was just one of many superstitions, since they seem totally unreasonable and since God is in control of His Universe it can hardly be possible for human beings to frustrate His will by supernatural means. There are seemingly no references to the Evil Eye in Kabbalistic Literature such as the Sefer Yetzirah.
Oh, well. The World did not end on December 21, 2012. Kinnahora!