[A]ll that is conceivable in thought lies between two extremes, which, as contradictory of each other, can not both be true, but of which, as mutually contradictory, one must be true. . . .
Source: 'The Internet Encyclopedia of Philosophy.
-- William Hamilton, (Mar 8 1788-1856), Scottish philosopher; He contributed to the lively ecclesiastical controversy of the time [1843] by publishing a pamphlet against the principle of non-intrusion.