conspicuously dangerous to the thinker, the class of negative terms. The
negative term is in plain fact just nothing; "Not-A" is the absence of
any trace of the quality that constitutes A, it is the rest of
everything for ever. But there seems to be a real bias in the mind
towards regarding "Not-A" as a thing mysteriously in the nature of A, as
though "Not-A" and A were species of the same genus. When one speaks of
Not-pink one is apt to think of green things and yellow things and to
ignore anger or abstract nouns or the sound of thunder. And logicians,
following the normal bias of the mind, do actually present A and not-A
in this sort of diagram:--

(the letter A inside a circular boundary, together with the words Not A,
all inside a bigger circular boundary.)

ignoring altogether the difficult case of the space in which these words
are printed. Obviously the diagram that comes nearer experienced fact
is:--

(the word Not, followed by the letter A inside a circular boundary,
followed by the letter A)

with no outer boundary. But the logician finds it necessary for his
processes to present that outer Not-A as bounded (Vide e.g. Kayne's
"Formal Logic" re Euler's diagrams and Immediate Inferences.), and to
speak of the total area of A and Not-A as the Universe of Discourse; and
the metaphysician and the commonsense thinker alike fall far too readily
into the belief that this convention of method is an adequate
representation of fact.

Let me try and express how in my mind this matter of negative terms has