Or else, intensely aware of his own weaknesses and deformities and other men’s good qualities, conscious of his own small worth and merit, he distrusts himself—for what is jealousy but distrust? He suspects that she cannot love him, or is not as kind and loving as she should be: she must certainly love some other man better than him.

Nevizzano, in book 4, paragraph 72, makes barrenness a principal cause of jealousy. If her husband cannot perform as a man, someone else shall; they will leave no remedy untried, and thereupon the husband grows jealous. I could give an example, but let it stand as it is.

Some men give this reason: because they have previously been unfaithful themselves, they think others may treat them in the same way. They turned up trumps before the cards were shuffled; therefore they shall receive “the law of retaliation,” like for like.

Wretched that I am, I myself taught her how to deceive Her guards; alas, now my own skill is turned against me!

Wretch that I was, I taught her to be false, And now my own sly tricks are played on me.

“A bad mind, a bad disposition,” as the saying goes: bad dispositions breed bad suspicions.

I would stake my life that no man is jealous Except one who has defiled another’s wife; And because he himself has gone astray, He immediately thinks his wife will take that path.

To these two causes just named, or kindlers of this rage, I may well add the circumstances of time, place and people through which it ebbs and flows—the fuel of this fury, as Vives rightly observes—and similar accidents or occasions, arising from the partners themselves or from others, which greatly aggravate and intensify this suspicious disposition.

For many men are so lustfully inclined, either through a depraved nature or through the excessive freedom they claim because of their greatness as noblemen—for “licence to sin, and the multitude of sinners” are powerful inducements—that however beautiful, noble, virtuous, chaste, wise, vigorous and well-disposed their own wives may be, they must have a change.

Though bound by the covenant of lawful marriage To women distinguished in virtue, beauty and family, They still seek prostitutes and filthy whores in brothels, And try to pluck new pleasures through adultery.

Though married to wives most virtuous, Noble and beautiful, they stray in lust.

“What is permitted is unwelcome”: what is commonplace is displeasing. Nero, says Tacitus, detested his own wife Octavia, a noble and virtuous lady, and loved Acte, by comparison a lowly woman. Cerinthus rejected Sulpicia, a nobleman’s daughter, and courted a poor servant girl.

So great is the pleasure in another person’s harvest,

for “stolen waters are more pleasant”; or, as the emperor Vitellius used to say, “The more delightful loves are those pursued with danger.” Like stolen venison, the sweetest love is always that which is hardest to obtain. They prefer to hunt secretly in another man’s grounds rather than enjoy the finest possible chase after game of their own.

See how in heaven now the sun, now the moon performs its office; So too, for us one woman is not enough.

As sun and moon in heaven change their course, So they change lovers, though often for the worse.

Or some beautiful object moves them so powerfully that they cannot restrain themselves: whether they hear of it or see it, they will pursue it. Nessus the centaur had agreed to carry Hercules and his wife across the river Evenus. No sooner had he set Deianira on the other side than he tried to rape her, leaving Hercules to swim across as best he could. Although her husband was watching, he would not stop until Hercules shot him dead with a poisoned arrow.

Neptune happened to see Tyro of Thessaly, Eunippius’s wife, and immediately, in the frenzy of his lust, assumed her husband’s appearance and made him a cuckold. Tarquin heard Collatinus praise his wife, and was so inflamed that he went to her in the middle of the night. Theseus abducted Ariadne, “carried off by force” that Anaxa of Troezen, Antiope, and, when he was already old, Helen, a girl not yet ready for marriage.

Great men are, for the most part, all disposed this way: like horses they neigh, says Jeremiah, after their neighbours’ wives,

As a colt neighs at the sight of a mare.

And if they are in company with other women, even in their own wives’ presence, they must court and flirt with them. In Lucian, Juno complains that Jupiter kept kissing Ganymede before her very face, which offended her greatly. Besides, he impersonated Amphitryon, became a bull, a swan and a golden shower, and played many such wicked tricks, too lengthy and too shameful to relate.

Or they care little for their own ladies and fear no laws, daring openly to keep prostitutes under their wives’ noses. Unchastity is all too common among noblemen. “Piety, integrity and fidelity are private virtues,” as someone said long ago: piety, chastity and similar virtues are for private men, and are scarcely to be sought in great courts.

And what Suetonius said of the good princes of his time—that they could all be engraved on a single ring—we may truly say of the chaste rulers of our age. For great personages commonly go astray in this way and give cause for offence.

Montaigne, in his Essays, gives examples in Caesar, Mehmed the Turk, who sacked Constantinople, and Ladislaus, king of Naples, who besieged Florence. Great men and great soldiers are commonly great—and so forth. “It is proved”: they are good performers. Mars and Venus are evenly matched in their activities,

Doves have made their nest in a soldier’s helmet; It is clear how friendly Venus is with Mars.

A dove made her nest inside a helmet: See the bond between Mars and Venus.

Especially if they are bald, for bald men have always been suspect—read more in Aristotle, section 4, problem 19—such as Galba, Otho, Domitian and, conspicuous among them, Caesar. “Citizens, guard your wives: we are bringing home the bald adulterer.”

Besides, this bald Caesar, says Curio in Suetonius, was “every woman’s husband.” He made love to Eunoë, queen of Mauretania; Cleopatra; Postumia, wife of Sergius Sulpitius; Lollia, wife of Gabinius; Tertulla, wife of Crassus; Mucia, Pompey’s wife; and I do not know how many others. And well he might, for if everything I have read is true, he had a licence to sleep with whomever he pleased.