But Mr. Taylor's statement though clear, I think, with regard to the meaning of _percipi_ is highly ambiguous in other respects. I will leave it for the present to consider the next ambiguity in the statement: _Esse_ is _percipi._ What does the copula mean? What can be meant by saying that Esse _is_ percipi? There are just three meanings, one or other of which such a statement _must_ have, if it is to be true; and of these there is only one which it can have, if it is to be important. (1) The statement may be meant to assert that the word 'esse' is used to signify nothing either more or less than the word 'percipi': that the two words are precise synonyms: that they are merely different names for one and the same thing: that what is meant by _esse_ is absolutely identical with what is meant by _percipi._ I think I need not prove that the principle _esse_ is _percipi_ is _not_ thus intended merely to define a word; nor yet that, if it were, it would be an extremely bad definition. But if it does _not_ mean this, only two alternatives remain. The second is (2) that what is meant by _esse,_ though not absolutely identical with what is meant by _percipi_, yet _includes_ the latter as a _part_ of its meaning. If this were the meaning of 'esse is percipi,' then to say that a thing was real would not be the same thing as to say that it was experienced. That it was _real_ would mean that it was experienced and _something else besides_: 'being experienced' would be _analytically essential_ to reality, but would not be the whole meaning of the term. From the fact that a thing was real we should be able to infer, by the law of contradiction, that it was experienced; since the latter would be _part_ of what is meant by the former. But, on the other hand, from the fact a thing was experienced we should _not_ be able to infer that it was real; since it would not follow from the fact that it had one of the attributes essential to reality, that it _also_ had the other or others. Now, if we understand _esse_ is _percipi_ in this second sense, we must distinguish _three_ different things which it asserts. First of all, it gives a definition of the word 'reality,' asserting that word stands for a complex whole, of which what is meant by 'percipi' forms a part. And secondly it asserts that 'being experienced' forms a part of a certain whole. Both these propositions may be true, and at all events I do not wish to dispute them. I do not, indeed, think that the word 'reality' is commonly used to include 'percipi': but I do not wish to argue about the meaning of words. And that many things which are experienced are also something else--that to be experienced forms part of certain wholes, is, of course, indisputable. But what I wish to point out is, that neither of these propositions is of any importance, unless we add to them a _third._ That 'real' is a convenient name for a union of attributes which _sometimes_ occurs, it could not be worth any one's while to assert: no inferences of any importance could be drawn from such an assertion. Our principle could only mean that when a thing happens to have _percipi_ as well as the other qualities included under _esse,_ it has _percipi_: and we should never be able to _infer_ that it was experienced, except from a proposition which already asserted that it was both experienced and something else. Accordingly, if the assertion that _percipi_ forms part of the whole meant by reality is to have any importance, it must mean that the whole is organic, at least in this sense, that the other constituent or constituents of it _cannot_ occur without percipi, even if percipi can occur without them. Let us call these other constituents _x._ The proposition that _esse_ includes _percipi,_ and that therefore from _esse percipi_ can be inferred, can only be important if it is meant to assert that _percipi_ can be inferred from _x._ The only importance of the question whether the whole _esse_ includes the part _percipi_ rests therefore on the question whether the part _x_ is necessarily connected with the part _percipi._ And this is (3) the third possible meaning of the assertion _esse is percipi:_ and, as we now see, the only important one. _Esse_ is _percipi_ asserts that wherever you have _x_ you also have _percipi_ that whatever has the property _x_ also has the property that it is _experienced._ And this being so, it will be convenient if, for the future, I may be allowed to use the term '_esse_' to denote _x alone._ I do not wish thereby to beg the question whether what we commonly mean by the word 'real' does or does not include _percipi_ as well as _x._ I am quite content that my definition of 'esse' to denote _x_, should be regarded merely as an arbitrary verbal definition.