Friendly Observations
I must warn against an opposite error—namely, that if Reason, as distinguished from Prudence, consists merely in knowing that Black cannot be White—or when a man has a clear conception of an inclosed figure, and another equally clear conception of a straight line, his Reason teaches him that these two conceptions are incompatible in the same object, i.e. that two straight lines cannot include a space—the said Reason must be a very insignificant faculty. But a moment’s steady self-reflection will shew us, that in the simple determination “Black is not White”—or, “that two straight lines cannot include a space”— all the powers are implied, that distinguish Man from Animals—first, the power of reflection—2d. of comparison—3d. and therefore of suspension of the mind—4th. therefore of a controlling will, and the power of acting from notions, instead of mere images exciting appetites; from motives, and not from mere dark instincts.
Samuel Taylor Coleridge