And first with regard to _percipi._ This term need not trouble us long at present. It was, perhaps, originally used to mean 'sensation' only; but I am not going to be so unfair to modern Idealists--the only Idealists to whom the term should now be applied without qualification--as to hold that, if they say _esse_ is _percipi_, they mean by _percipi_ sensation only. On the contrary I quite agree with them that, if _esse_ be _percipi_ at all, _percipi_ must be understood to include not sensation only, but that other type of mental fact, which is called 'thought '; and, whether _esse_ be _percipi_ or not, I consider it to be the main service of the philosophic school, to which modern Idealists belong, that they have insisted on distinguishing 'sensation' and 'thought' and on emphasising the importance of the latter. Against Sensationalism and Empiricism they have maintained the true view. But the distinction between sensation and thought need not detain us here. For, in whatever respects they differ, they have at least this in common, that they are both forms of consciousness or, to use a term that seems to be more in fashion just now, they are both ways of experiencing. Accordingly, whatever _esse_ is _percipi_ may mean, it does _at least_ assert that whatever is, is _experienced._ And since what I wish to maintain is, that even this is untrue, the question whether it be experienced by way of sensation or thought or both is for my purpose quite irrelevant. If it be not experienced at all, it cannot be either an object of thought or an object of sense. It is only if being involves 'experience' that the question, whether it involves sensation or thought or both, becomes important. I beg, therefore, that _percipi_ may be understood, in what follows, to refer merely to what is _common_ to sensation and thought. A very recent article states the meaning of _esse_ is _percipi_ with all desirable clearness in so far as _percipi_ is concerned. 'I will undertake to show,' says Mr. Taylor,[1] 'that what makes [any piece of fact] real can be nothing but its presence as an inseparable aspect of _a sentient experience_.' I am glad to think that Mr. Taylor has been in time to supply me with so definite a statement that this is the ultimate premiss of Idealism. My paper will at least refute Mr. Taylor's Idealism, if it refutes anything at all: for I _shall_ undertake to show that what makes a thing real cannot possibly be its presence as an inseparable aspect of a senient experience.