STRANGER: My notion would be, that anything which possesses any sort of power to affect another, or to be affected by another, if only for a single moment, however trifling the cause and however slight the effect, has real existence; and I hold that the definition of being is simply power.
THEAETETUS: They accept your suggestion, having nothing better of their own to offer.
STRANGER: Very good; perhaps we, as well as they, may one day change our minds; but, for the present, this may be regarded as the understanding which is established with them.
THEAETETUS: Agreed.
STRANGER: Let us now go to the friends of ideas; of their opinions, too, you shall be the interpreter.
THEAETETUS: I will.
STRANGER: To them we say—You would distinguish essence from generation?
THEAETETUS: 'Yes,' they reply.
STRANGER: And you would allow that we participate in generation with the body, and through perception, but we participate with the soul through thought in true essence; and essence you would affirm to be always the same and immutable, whereas generation or becoming varies?
THEAETETUS: Yes; that is what we should affirm.