Again, these pleasures are pursued because of their intensity by those who are unable to take delight in other pleasures; thus we see people make themselves thirsty on purpose. When the pleasures they pursue are harmless, we do not blame them (though when they are hurtful the pursuit is bad); for they have no other sources of enjoyment, and the neutral state is painful to many because of their nature: for an animal is always labouring, as physical science teaches, telling us that seeing and hearing is labour and pain, only we are all used to it, as the saying is. And thus in youth, because they are growing, men are in a state resembling drunkenness; and youth is pleasant. But people of a melancholic nature are always wanting something to restore their balance; for their bodies are always vexing them because of their peculiar temperament, and they are always in a state of violent desire. But pain is expelled either by the opposite pleasure or by any pleasure, if it be sufficiently strong; and this is the reason why such men become profligate and worthless.