Our wavering between logical and physical impossibility makes us make such statements as this: “If what I feel is always my pain only, what can the supposition mean that someone else has pain?” The thing to do in such cases is always to look how the words in question are actually used in our language. We are in all such cases thinking of a use different from that which our ordinary language makes of the words. Of a use, on the other hand, which just then for some reason strongly recommends itself to us. When something seems queer about the grammar of our words, it is because we are alternately tempted to use a word in several different ways. And it is particularly difficult to discover that an assertion which the metaphysician makes expresses discontentment with our grammar when the words of this assertion can also be used to state a fact of experience. Thus when he says “only my pain is real pain”, this sentence might mean that the other people are only pretending. And when he says “this tree doesn't exist when nobody sees it”, this might mean: “this tree vanishes when we turn our backs to it”. The man who says “only my pain is real”, doesn't mean to say that he has found out by the common criteria ‒ ‒ ‒ the criteria, i.e., which give our words their common meanings ‒ ‒ ‒ that the others who said they had pains were cheating. But what he rebels against is the use of this expression in connection with these criteria. That is, he objects to using this word in the particular way in which it is commonly used. On the other hand, he is not aware that he is objecting to a convention. He sees a way of dividing the country different from the one used on the ordinary map. He feels tempted, say, to use the name “Devonshire” not for the county with its conventional boundary, but for a region differently bounded. He could express this by saying: “Isn't it absurd to make this a county, to draw the boundaries here?” But what he says is: “The real Devonshire is this”. We could answer: “What you want is only a new notation, and by a new notation no facts of geography are changed”. It is true, however, that we may be irresistibly attracted or repelled by a notation. (We easily forget how much a notation, a form of expression, may mean to us, and that changing it isn't always as easy as it often is in mathematics or in the sciences. A change of clothes or of names may mean very little and it may mean a great deal.)