Rabbi Yochanan, the third century scholar, had an unusual custom. He would sometimes sit down outside the town mikveh (ritual bath). This way, he explained, the Jewish women will see me as they leave the bath and will have children as beautiful as me. Rabbi Yochanan’s colleagues asked him: Are you not afraid of the Evil Eye?
“'I am descended from Joseph,’ he replied, ‘and the Evil Eye had no power over him.'” (Berachot 20a)
Apart from the issue of Rabbi Yochanan’s beauty, this story raises some interesting questions. What is the Evil Eye? Is it just a primitive superstition? And why was Joseph, more than any other Biblical figure, immune from it?
The Talmud explains that Joseph merited protection from the Evil Eye since “his eye did not wish to benefit from that which did not belong to him.” Despite Mrs. Potiphar’s attempts to seduce him, Joseph remained faithful to God and his employer. Truly an act of great moral integrity — but what does this have to do with the Evil Eye?
Rav Kook explained that the Evil Eye is an example of how one soul may affect another through unseen connections between them. We are all influenced by our environment. Living among the refined and the righteous has a strong positive effect, while living among the crass and the corrupt has a negative one. The Evil Eye is simply the venomous impact from malignant feelings of jealousy and envy of those around us.
A person who has hardened his inner resolve and does not allow himself to be misled from the correct path, despite outside pressures — such a person has built a ‘firewall’ protecting his soul from external influences. The Biblical hero who most prominently demonstrated this strength of character and refusal to be led astray is Joseph. Seventeen years old, young and handsome, estranged from the protective framework of his family and culture, a slave propositioned by a powerful and attractive woman, Joseph nevertheless beat the odds and remained faithful to his ideals. Joseph determined that he would not be swayed by his surroundings, no matter how persuasive. Through his heroic stance, he merited that the Evil Eye would have no power over him and his descendants.
(Gold from the Land of Israel, pp. 86-87. Adapted from Ein Eyah vol. I, p. 102)