208 Transactions.— Miscellaneous. 
among these, which constitute the whole content of physical science, there 
exists a universe of realities inaccessible to physical science, on which the 
possibilities of sensation are dependent. In the language of metaphysics 
the question may be thus stated :—Does the phenomenal world, or world of 
appearances, correspond to and depend for its existence on a noumenal world, 
or world of realities, wholly outside us? The answer given by the majo- 
rity of metaphysicians is, I believe, that there does exist such a world of 
realities, but that its nature must be for ever hidden from us. 
Physical science, they would say, investigates the properties of things 
as they appear to us—investigates the outsides of things, so to speak; but 
things as they are in themselves, the inner nature or insides of things (though 
we may be certain of their existence, whether intuitively or as a result of 
legitimate inference), are inaccessible to human research. This I take to 
be the doctrine of Kant, and also the doctrine of Herbert Spencer. Now, 
the doctrine I wish to describe this evening, is partly in agreement with the 
foregoing doctrine, and partly in disagreement with it. There is a universe 
of realities, it affirms, underlying the phenomena which it is the business 
of physical science to investigate, but its nature is not wholly unknown to 
us. For let us consider a particular section of physiological phenomena— 
the phenomena of the human brain. In the changes which take place, 
during life, in the grey matter of the brain, we have a field for physical 
research. These changes belong to the world of phenomena—to the world 
of “ things as they appear to us." They may be described in the language 
of physical science, and statements respecting them would resolve them- 
selves, in last analysis, into statements of possibilities of sensation, and 
relations among those possibilities, in the mind of a supposed observer. 
But now, according to both the doctrines we are considering, this complex 
of phenomena—this group of changes in the grey matter of the brain— 
must have a complex of noumena, or “ things-in-themselves," underlying it. 
What is this complex of “ things-in-themselves?” It is not an object of 
physical research. Physical research stops at the changes in the grey 
matter of the brain—stops at a group of appearances. What is the complex 
of “ things-in-themselves’’ which underlies these appearances? Now we 
know, or at least have very strong ground for believing, that some of the 
changes in the grey matter of the brain correspond to feelings or thoughts 
in the mind of the person to whom the brain belongs. Accordiny to the 
doctrine of Mind-Stuff, these feelings or thoughts are the nowmena—the ** things- 
in-themselves "—which underlie the changes in the grey matter of the brain. 
What appears to an outside observer—or rather, what would appear to him, 
were the skull transparent, as a change in the grey matter of the brain—is 
in reality a feeling or thought in the mind of the person to whom the brain 
