as it is asserted in some schools of thought, for an empty term could
express no idea, whereas this idea is perfectly clear. Neither is it a
real thing, but rather an ideal reality, not a pure abstraction of the
spirit, extracted, so to speak, from the material substance. The
conception of whiteness formed by the comparative judgment is limited by
the perception of the concrete, external fact perceived as one special
quality among all other qualities in nature, and it is therefore a
physiological fact of inward consciousness.

In the abstract idea of white or whiteness we do not only picture to
ourselves a quality common to many things, but by this term, and by the
idea which corresponds to it, the same sensation is actually present to
our inward intuition, or the same quality of the sensation which was
previously generated by our external senses in a concrete form.
Although, therefore, the idea is generic, the sensation itself is
represented to the mind in the form of a concrete perception. It is not
concrete in the sense of belonging to a special object or definite form,
as it is presented to the outward perception, but only so far as there
is actually an inward and physiological sensation of whiteness, which
the word recalls to the memory. There can be no mental confusion with
the quality of red, or of any colour, when I speak or think of what is
white.

When I speak or think of any object as white, I and others perfectly
understand what is meant, and a representation of this quality is
instantly formed in our minds, in the generic type which was gradually
constituted by primitive man by the combination of numerous special
sensations, obvious to the sight, and subsequently expressed in speech.

In order that the word which corresponds to the quality may have a given