If a dry bone is smeared with blood a dog will gnaw at it until she is tired and frustrated. Lust to a man is precisely like this bone to a dog; he will covet it until he is exhausted.
If a single piece of carrion is thrown to two wild beasts they will fight and claw each other to get it. A man foolish enough to carry a torch against the wind will likely burn himself. Like these two beasts and this foolish man, people hurt and burn themselves because of their worldly desires.