Jealousy: its different meanings, name, definition, extent and various kinds; among rulers, parents and friends; in animals and human beings; before marriage, as rivals, or afterwards, as discussed here.

Valescus de Taranta, in his chapter on melancholy, Elia Montalto, Felix Platter and Guaineri classify jealousy as a cause of melancholy; others call it a symptom, because melancholy people are especially susceptible to it among the mind’s passions and disturbances.

But I think that, because of its range and its prominence above other ordinary symptoms, it deserves to be treated as a separate species: it is so great and conspicuous a matter, so furious a passion, and almost as widespread as love itself. As Benedetto Varchi holds, “There is no love without some jealousy”; “he who is not jealous does not love.”

For these reasons I shall expand upon it and treat it separately, as an illegitimate offshoot or kind of love melancholy. Whereas passionate love commonly precedes marriage, jealousy usually follows it, torturing and tormenting in the same way. It therefore deserves similar treatment and requires equal care and effort in setting out its various causes, prognoses and cures.

I have undertaken this all the more willingly so that anyone who is or has been jealous may see his error as in a mirror; anyone who has not may learn to detest it, avoid it himself, and free others who are affected by it in any way.

Jealousy is described and defined as “a suspicion the lover has about the person he chiefly loves, lest he or she should fall in love with someone else”; or an eager desire to enjoy a beautiful person alone, to have that person exclusively to himself: a fear or doubt that an outsider might participate or share in his love.

Or, as Scaliger adds, “a fear of losing the favour of the woman he so earnestly loves.” Cardano calls it “a zeal for love, and a kind of envy lest someone should deceive us.” Juan Luis Vives defines it in the same words, or with little difference in meaning.

There are many other kinds of jealousy, though all are improperly called so: that of parents, tutors and guardians concerning their children, friends they love, or people entrusted to their care or protection.

Storax! Has Aeschinus not returned from dinner tonight, Nor any of the servants who went out to meet him?

So the old man in the comedy cried out in agitation, from anxious fear and concern for his adopted son: “not about beauty, but lest they should come to harm, do wrong, or in any way discredit, disgrace”—as Vives observes—“or endanger themselves and us.”

Aegeus was similarly anxious about his son Theseus’s success when he went to fight the Minotaur, fearing he might be defeated: “Fear is always inclined to believe the worse.”

We are always inclined to suspect the worst in such uncertain cases, as many wives do in their husbands’ absence, or doting mothers in their children’s, fearing that while away they may be led astray or fall ill. They continually await news of how they are faring and what has become of them; they cannot bear to have them long out of sight: “Oh, my sweet son! Oh, my dear child!” and so on.

Paul was jealous over the church at Corinth, as he acknowledges in 2 Corinthians 11:12, “with a godly jealousy, to present them as a pure virgin to Christ”; and he remained afraid that, as the serpent deceived Eve through his cunning, their minds might be corrupted away from simplicity in Christ.

God himself is said to be jealous in a certain sense: “I am a jealous God, and will visit”; likewise Psalm 79:5, “Shall your jealousy burn like fire for ever?” But these are called jealousies only figuratively, by a metaphor expressing care and concern for those in question.

Yet some jealousies display all the symptoms of the kind we are discussing—fear, sorrow, anguish, anxiety, suspicion, hatred and so forth—with only the object changed. That of some fathers towards their sons and heirs is especially marked. Although they love them dearly as children, they can scarcely tolerate them as they approach adulthood. The son and heir is commonly tired of his father, and the father in turn can scarcely endure his eldest son: “hence grudges, and very often quarrels and enmities.”

But the jealousy of rulers is most notorious, as when they fear rivals, if I may call them so: successors, competitors, subjects, or people they have offended. “All power will be intolerant of a partner.” “They are always suspicious, lest their authority be diminished,” as one observer remarks.

And as Commynes puts it, “It cannot be expressed how slight are the causes of their distress and suspicion: a secret disease that commonly lurks and breeds in rulers’ households.”

Sometimes it concerns their honour alone, as with the emperor Hadrian, “who killed all his rivals.” Saul envied David; Domitian envied Agricola because he surpassed him, overshadowing his honour, as he thought, and eclipsing his fame.

Juno turned Proetus’s daughters into cows because they competed with her in beauty. The Cyparissae, King Eteocles’s children, were envied by the goddesses for their excellent accomplishments, including dancing, says Constantine, “and for that reason were thrown headlong from heaven and buried in a pit; but the earth took pity on them and brought forth cypress trees to preserve their memory.” Niobe, Arachne and Marsyas can testify to as much.

But jealousy is most grievous when it concerns a kingdom itself or material interests. It produces lamentable effects, especially among tyrants, “under despotic rule,” and those whom their subjects fear more than love, who gain and retain sovereignty through force and fear: “which you know you hold against your citizens’ will,” and so forth, as Phalaris, Dionysius and Periander held theirs.

For although fear, cowardice and jealousy are, in Plutarch’s opinion, the common causes of tyranny, as in Nero, Caligula and Tiberius, most people take them to be symptoms.