No other interval carries an equivalent ambivalence or affect. The major seventh simultaneously belongs to its tonic and nevertheless sounds a world apart. By comparison, the tritone belongs to the major scale only as a matter of technicality; its dissonance is total, so much so that it is caricatured. Far from this crass and cartoonish dissonance, the major seventh uses dissonance to achieve transcendence. Or: the major seventh is beautiful by and through its very dissonance, through its long distance from tonic that is also the shortest distance possible.
(Chapter Four, Footnote 6)