Chapter IV

) that physical phenomena are not the only phenomena of which we have experience. We are conscious of mental phenomena as well, of the phenomena of the subjective order, of sensations and ideas. Why not admit that these _constitute_ the mind, as physical phenomena constitute the things which belong to the external world?

He who says this says no more than that the mind is known and is knowable. It is what it is perceived to be; and the more we know of mental phenomena, the more do we know of the mind. Shall we call the mind as thus known a _substance_? That depends on the significance which we give to this word. It is better, perhaps, to avoid it, for it is fatally easy to slip into the old use of the word, and then to say, as men have said, that we do not know the mind as it is, but only as it appears to us to be--that we do not know the reality, but only its appearances.

And if we keep clearly before us the view of the mind which I am advocating, we shall find an easy way out of the difficulties that seem to confront us when we consider it as nonextended and immaterial.

Certain complexes of mental phenomena--for example, the barber's pole above alluded to--certainly appear to be extended. Are they really extended? If I imagine a tree a hundred feet high, is it really a hundred feet high? Has it any real size at all?

Our problem melts away when we realize what we mean by this "real size." In