And now arises the greatest difficulty of all. If not-being is inconceivable, how can not-being be refuted? And am I not contradicting myself at this moment, in speaking either in the singular or the plural of that to which I deny both plurality and unity? You, Theaetetus, have the might of youth, and I conjure you to exert yourself, and, if you can, to find an expression for not-being which does not imply being and number. 'But I cannot.' Then the Sophist must be left in his hole. We may call him an image-maker if we please, but he will only say, 'And pray, what is an image?' And we shall reply, 'A reflection in the water, or in a mirror'; and he will say, 'Let us shut our eyes and open our minds; what is the common notion of all images?' 'I should answer, Such another, made in the likeness of the true.' Real or not real? 'Not real; at least, not in a true sense.' And the real 'is,' and the not-real 'is not'? 'Yes.' Then a likeness is really unreal, and essentially not. Here is a pretty complication of being and not-being, in which the many-headed Sophist has entangled us. He will at once point out that he is compelling us to contradict ourselves, by affirming being of not-being. I think that we must cease to look for him in the class of imitators. But ought we to give him up? 'I should say, certainly not.' Then I fear that I must lay hands on my father Parmenides; but do not call me a parricide; for there is no way out of the difficulty except to show that in some sense not-being is; and if this is not admitted, no one can speak of falsehood, or false opinion, or imitation, without falling into a contradiction. You observe how unwilling I am to undertake the task; for I know that I am exposing myself to the charge of inconsistency in asserting the being of not-being. But if I am to make the attempt, I think that I had better begin at the beginning. Lightly in the days of our youth, Parmenides and others told us tales about the origin of the universe: one spoke of three principles warring and at peace again, marrying and begetting children; another of two principles, hot and cold, dry and moist, which also formed relationships. There were the Eleatics in our part of the world, saying that all things are one; whose doctrine begins with Xenophanes, and is even older. Ionian, and, more recently, Sicilian muses speak of a one and many which are held together by enmity and friendship, ever parting, ever meeting. Some of them do not insist on the perpetual strife, but adopt a gentler strain, and speak of alternation only. Whether they are right or not, who can say? But one thing we can say--that they went on their way without much caring whether we understood them or not. For tell me, Theaetetus, do you understand what they mean by their assertion of unity, or by their combinations and separations of two or more principles? I used to think, when I was young, that I knew all about not-being, and now I am in great difficulties even about being.