this group.

It is necessary therefore to amend Hume's primary "geography of the
mind" by the excision of one territory and the addition of another; and
the elementary states of consciousness will stand thus:--

A. IMPRESSIONS.
A. Sensations of
_a._ Smell.
_b._ Taste.
_c._ Hearing.
_d._ Sight.
_e._ Touch.
_f._ Resistance (the muscular sense).
B. Pleasure and Pain.
C. Relations.
_a._ Co-existence.
_b._ Succession.
_c._ Similarity and dissimilarity.
B. IDEAS.
Copies, or reproductions in memory, of the foregoing.

And now the question arises, whether any, and if so what, portion of
these contents of the mind are to be termed "knowledge."

According to Locke, "Knowledge is the perception of the agreement or
disagreement of two ideas;" and Hume, though he does not say so in so
many words, tacitly accepts the definition. It follows, that neither
simple sensation, nor simple emotion, constitutes knowledge; but that,
when impressions of relation are added to these impressions, or their
ideas, knowledge arises; and that all knowledge is the knowledge of
likenesses and unlikenesses, co-existences and successions.

It really matters very little in what sense terms are used, so long as
the same meaning is always rigidly attached to them; and, therefore, it
is hardly worth while to quarrel with this generally accepted, though
very arbitrary, limitation of the signification of "knowledge." But, on
the face of the matter, it is not obvious why the impression we call a
relation should have a better claim to the title of knowledge, than that
which we call a sensation or an emotion; and the restriction has this
unfortunate result, that it excludes all the most intense states of
consciousness from any claim to the title of "knowledge."

For example, on this view, pain, so violent and absorbing as to exclude
all other forms of consciousness, is not knowledge; but becomes a part
of knowledge the moment we think of it in relation to another pain, or
to some other mental phenomenon. Surely this is somewhat inconvenient,
for there is only a verbal difference between having a sensation and
knowing one has it: they are simply two phrases for the same mental
state.

But the "pure metaphysicians" make great capital out of the ambiguity.
For, starting with the assumption that all knowledge is the