Pitigrilli said this quote

“ Jealousy is a fever that arises from a stupid, baseless excitement in our unthinking brain.Jealousy is a phenomenon of auto-suggestion.The woman you love has gone to bed with X. You hate X, you hate her, and you have perpetually before your eyes the vision of your loved one and X embracing in an act that fills you with horror.But you too in your time have deceived the woman you love and have done with Y what X did in bed with woman you love.Well, what remains in your skin ,your mind of Mrs Y? Nothing whatever. No more than X left with your woman.In other words, auto suggestion. Do you want evidence of that? Well, then, if you don't know the man, you imagine him to be hateful, offensive, repulsive, and you feel that if you met him you'd kill him.But, if you happen to see his photograph, you begin to realize that it's possible to look at him without horror; and believe me, if you were actually introduced to him you'd approach him with a cordial smile on your lips, look him in the eye without trembling and, if you have reached my degree of perfection, you'd actually be capable of cheerfully patting him on the back and telling him he's a good chap.In a not too distant future, reason and education will have driven home the lesson of the futility of jealousy. ”