Metaphysics

​And closely related to what has been said is also what was stated by Protagoras; for he too said that man is the measure of all things, meaning nothing other than that what seems to each person is also what securely exists. But if this is so, it follows that the same thing both is and is not, and is both bad and good, and the other things that are stated according to opposite assertions, because often to some people this seems to be beautiful, but to others the opposite, and what seems to each is the measure. This difficulty would be resolved if we consider whence the origin of this belief has arisen; for it seems to have arisen for some from the opinion of the natural philosophers, and for others from the fact that not all people judge the same things in the same way, but to some this seems sweet (pleasant), while to others the opposite. For that nothing comes to be from non-being, but everything from being, is a common doctrine of almost all who study nature. Since, then, what becomes white does not come to be from that which is perfectly white and in no way non-white, that which becomes white would come to be from non-white being. Therefore, according to them, it would come to be from non-being unless the same thing were already both white and non-white. But it is not difficult to resolve this difficulty; for it has been stated in the *Physics* how things that come to be do so from non-being, and how from being. However, to pay equal attention to the opinions and appearances of those who dispute with one another is foolish; for it is clear that one of the two parties must necessarily be mistaken. And this is clear from what happens in sensation; for the same thing never appears sweet to some and the opposite to others, unless the sense organ, which is the criterion of the mentioned tastes, of one of the parties is destroyed and damaged. And since this is so, one of the parties must be assumed to be the measure, and the others must not be assumed as such. I say the same likewise concerning good and bad, and beautiful and ugly, and other such things. For to maintain this is no different from claiming that, to those who press a finger under the eye and make one thing appear to be two, there must be two because they appear so many, and again one; for to those who do not move their eye, the one appears as one. Generally, it is absurd to make our judgment about truth from the fact that things here are changing and never remain in the same state; for we must hunt for the truth from things which are always in the same state and undergo no change, and such are the things in the cosmos; for these do not appear now of one sort and then of another, but are always the same and share in no change. Furthermore, if motion exists, there is also something being moved, and everything that is moved is moved from something and into something. Therefore, that which is being moved must both be in that from which it is to be moved, and not be in it, and must be moved into this other and be coming to be in it, and so the contradiction cannot be true at the same time, according to them.