whether a red patch exists, is precisely the sense in which they admit that my perception of a red patch does exist. And in this sense, it is plain that to suppose that a thing may exist, which is not perceived, or that it may _not_ exist, although it is perceived, is at least not self-contradictory. But there may be other philosophers who will say that, in the case of a perception also, to say that it exists or is real is to say that it is perceived--either that alone or something more as well. And to these philosophers I would first point out that they are admitting that the proposition "This perception is real" is significant. There is some sense or other in which we may say: "Alexander's perception of an elephant was real or did exist, but Sindbad's perception of a Roc was _not_ real--never did exist": the latter proposition is, in some sense or other, not self-contradictory. And then I would ask of them: When they say, that to call a perception "real" is to assert that it is perceived, do they mean by this that to call it real is to assert that it is _really_ perceived, or not? If they say "No," then they are asserting that to call a perception "real" is merely to say that it was perceived in the sense in which Sindbad _did_ perceive a Roc: they are asserting that to call it "real" is not to say, in any sense, that it was _really_ perceived: they are asserting that to call a perception "real" is to say that it was perceived, in some sense quite other than that in which we ordinarily use the word: for we certainly commonly mean, when we say "A was perceived," that a perception of A was "real": we should commonly say that Sindbad did _not_ perceive a Roc--meaning that no such perception ever did exist. I do not think they do mean this; and, in any case, if they do, I think it is plain that they are wrong. When we say that a perception is "real," we certainly do not mean merely that it is the object of another perception, which may itself be quite unreal--purely Imaginary. I assume, therefore, that when they say: To call a perception "real" is to say that it is perceived; they mean, what we should naturally understand, namely, that: To call it "real" is to say that it is _really_ perceived--to say that it is the object of another perception, which is also _real_ in the same sense. And, if they mean this, then what they say is certainly untrue. Their definition of reality is circular. It cannot be the case that the _only_ sense in which a perception may be said to be real, is one in which to call it so is to assert that not it alone, but another perception is real also. It cannot be the case that the assertion "A is real" is _identical_ with the assertion "A and B are both real," where A and B are different, and "real" is used in the same sense as applied to both. If it is to be true that the assertion "A is real" _ever_, in any sense, includes the assertion "A is _really_ perceived," there must