The first sentence of Plato's Republic recounts how Socrates went on a journey of descent – a katabasis – leaving the secure walls of Athens in order to celebrate the introduction of a new worship:

With this opening metaphor of descent – and continuing on through its central books of ascent to the final mythical katabasis and revelatory reascent (anabasis) of the Myth of Er (614b–621d) – Plato's Republic announces itself to be an original and revolutionary journey toward the truth, passing through extraordinarily mysterious terrain. This opening also suggests what the text goes on to confirm, namely, that the purpose of the Republic is to introduce a new cult outside the walls of the traditional dispensation. The divinity of this sect proves not to be a Thracian night-goddess, however, but the Reality of the Form-world, and its new worship involves not nocturnal horse races (328a), but the intellectual activity of philosophizing whose sacrificial rewards are threefold: wisdom, happiness, and the assurance of immortality.