May it not be, if we really are shut up to the circle of our experiences, that the physical things, which we have been accustomed to look upon as non-mental, are nothing more than complexes of sensations?
Granted that there seems to be presented in our experience a material world as well as a mind, may it not be that this material world is a mental thing of a certain kind--a mental thing contrasted with other mental things, such as imaginary things?
This question has always been answered in the affirmative by the idealists, who claim that all existence must be regarded as psychical existence.

Their doctrine we shall consider later (sections 49 and 53).

It will be noticed that we seem to be back again with Professor Pearson in the last chapter.
To this question I make the following answer: In the first place, I remark that even the plain man distinguishes somehow between his sensations and external things.

He thinks that he has reason to believe that things do not cease to exist when he no longer has sensations.

Moreover, he believes that things do not always appear to his senses as they really are.