After reviewing the psychoanalytic literature on the subject, the author elaborates three aspects: first, the jealous person enjoys the pleasure of peeping. Second, the painfulness of jealousy is caused by feelings of guilt because the loved person represents the ego ideal; thus the jealous person is disappointed by his own ego ideal. Third, activity or passivity decide whether the jealous person attacks the rival or the loved object. The author does not present clinical material to confirm his views, but refers mainly to his earlier studies.