YOUNG SOCRATES: Why is that?
STRANGER: Why, because only the most divine things of all remain ever unchanged and the same, and body is not included in this class. Heaven and the universe, as we have termed them, although they have been endowed by the Creator with many glories, partake of a bodily nature, and therefore cannot be entirely free from perturbation. But their motion is, as far as possible, single and in the same place, and of the same kind; and is therefore only subject to a reversal, which is the least alteration possible. For the lord of all moving things is alone able to move of himself; and to think that he moves them at one time in one direction and at another time in another is blasphemy. Hence we must not say that the world is either self-moved always, or all made to go round by God in two opposite courses; or that two Gods, having opposite purposes, make it move round. But as I have already said (and this is the only remaining alternative) the world is guided at one time by an external power which is divine and receives fresh life and immortality from the renewing hand of the Creator, and again, when let go, moves spontaneously, being set free at such a time as to have, during infinite cycles of years, a reverse movement: this is due to its perfect balance, to its vast size, and to the fact that it turns on the smallest pivot.
YOUNG SOCRATES: Your account of the world seems to be very reasonable indeed.
STRANGER: Let us now reflect and try to gather from what has been said the nature of the phenomenon which we affirmed to be the cause of all these wonders. It is this.
YOUNG SOCRATES: What?
STRANGER: The reversal which takes place from time to time of the motion of the universe.
YOUNG SOCRATES: How is that the cause?
STRANGER: Of all changes of the heavenly motions, we may consider this to be the greatest and most complete.
YOUNG SOCRATES: I should imagine so.
STRANGER: And it may be supposed to result in the greatest changes to the human beings who are the inhabitants of the world at the time.