concrete. That is so because they refer to exertional activities.
Abstract terms are terms abstracted from this dynamic reference. Thus
_white_ is concrete because colour is a property of the dynamic world.
But when this property is considered apart from its dynamic support it
is called _whiteness_, and becomes abstract. In the case of purely
mental qualities the term is regarded as abstract simply because the
quality is in every reference extra dynamic. Thus _candour_, _justice_
are called abstract terms; they are properties of the Mind. But a
property of the dynamic system, _e.g._ Gravitation, does not strike us
as abstract--the sole distinction being the dynamic reference which the
latter term implies.

It will even be seen that there is sometimes a shading off of abstract
quality. Thus _Justice_ as an attribute of the Mind strikes us as a
purely abstract term. But as the word takes up a dynamic reference so
does its abstraction diminish. Thus in the expression "Administration of
Justice" the abstractive suggestion is less pronounced; till in the
person of Justice Shallow it vanishes in the very concrete.

Behind and beneath all these considerations we should never lose sight
of the great main facts--that thought is an activity; that its function
therefore is to represent or reproduce our pure exertional activity;
that such representation is _at the basis_ of all our concepts of
externality; that sensation, _per se_ is mere interruption of activity;
that _per se_ it possesses no spatial or extensive or external
suggestiveness; that sensations nevertheless serve to denote or give
feature and particularity to our experience of activity; that all
perception of the external is at bottom therefore a mental
representation of exertional activity and its forms, denoted,
punctuated, identified by sensation, which latter by itself, we repeat,
carries no suggestion of externality. This view revolutionises the whole
psychology of Perception, and therefore, though it at once gives to that
science a much-needed unity, clarity, and simplicity, it will naturally
be accepted with reluctance by the laborious authors of the cumbrous
theories still generally current.

FOOTNOTES:

[18:1] His reason is that we _ab origine_ localise sensations with
reference to our organism. This, of course, means by reference to the
system of potent energy in which our organism essentially consists.

III

THE TWO TYPICAL THEORIES OF KNOWL