In Book I of the Republic, or so I shall argue, Plato gives us a glimpse of sheer horror. In the character, beliefs, and desires of Thrasymachus, Plato aims to personify some of the most diabolical dangers that lurk in human nature. In this way, the role that Thrasymachus plays for Plato is akin to the role that for Hobbes is played by the bellum omnium contra omnes, the war of all against all, which would allegedly be the inevitable result of a "state of nature", where human beings have no government to terrorize them into obedience. It is also akin to the role that for Kant is played by the "radical evil" that is allegedly an indelible feature of human nature itself. As I shall try to show, the desires that characterize Thrasymachus are of the kind that are described in Book IX as "lawless" desires, desire ofthe wild insane kind that dominate the tyrannical soul; and his beliefs systematically reflect these desires, in a way that has its own hideously coherent logic.