Hence the principle of Excluded Middle does not hold good of mere contrary terms.

If we deny that a leaf is green, we are not bound to affirm it to be yellow; for it may be red; and then we may deny both contraries, yellow and green.

In fact, two contraries do not between them cover the whole predicable area, but contradictories do: the form of their expression is such that (within the _suppositio_) each includes all that the other excludes; so that the subject (if brought within the _suppositio_) must fall under the one or the other.
It may seem absurd to say that Mont Blanc is either wise or not-wise; but how comes any mind so ill-organised as to introduce Mont Blanc into this strange company?
Being there, however, the principle is inexorable: Mont Blanc is not-wise.
In fact, the principles of Contradiction and Excluded Middle are inseparable; they are implicit in all distinct experience, and may be regarded as indicating the two aspects of Negation.

The principle of Contradiction says: _B is not both A and not-A_, as if _not-A_ might be nothing at all; this is abstract negation.

But the principle of Excluded Middle says: _Granting that B is not A, it is still something_--namely, _not-A_; thus bringing us back to the concrete experience of a continuum in which the absence of one thing implies the presence of something else.