The brother is not enamoured of his own sister, nor the father of his own daughter; some other man must be the lover.

Reverence and law are strong enough to break the heart of passion.

[11] But if a law were passed saying, 'Eat not, and thou shalt not starve; Drink not, and thou shalt not thirst; Let not cold bite thee in winter nor heat inflame thee in summer,' I say there is no law that could compel us to obey; for it is our nature to be swayed by these forces.

But love is voluntary; each man loves to himself alone, and according as he chooses, just as he chooses his cloak or his sandals." [12] "Then," said Cyrus, "if love be voluntary, why cannot a man cease to love when he wishes?
I have seen men in love," said he, "who have wept for very agony, who were the very slaves of those they loved, though before the fever took them they thought slavery the worst of evils.

I have seen them make gifts of what they ill could spare, I have seen them praying, yes, praying, to be rid of their passion, as though it were any other malady, and yet unable to shake it off; they were bound hand and foot by a chain of something stronger than iron.