common being the raised supertonic seventh, which resolves to the tonic in major keys (–I, shown below) and the raised submediant, which resolves to dominant triad or seventh in major keys (–V, shown right), with the altered tones resolving upward by half step in both cases. The ct7 chord, whose function, "is simply one of embellishment," most often spelled when embellishing I or when embellishing V, is distinguished from the vii7/V chord by common tone chords resolving to I or I while vii7/V resolves to V or I. They may be confused, due to enharmonic equivalency, but resolution is a better indicator of function than spelling. In C: ct7/I = d7 = D–F–A–C vii7/V = f7 = F–A–C–E (= D) The diminished chord may also resolve through lowering two of the chord tones producing a supertonic seventh chord (ii7) that may lead to a conventional cadence: Expressive potential During the Baroque era (1600–1750), European composers became aware of the expressive potential of the diminished seventh chord. In operas and other dramatic works, the chord was frequently used to heighten the sense of passion, anger, danger or mystery. One famous example can be found in J. S. Bach's St. Matthew Passion (1737), in which he sets verses from the Gospel of Matthew, chapter 27, verses 20–21: "But the chief priests and elders persuaded the multitude that they should ask Barabbas, and destroy Jesus. The governor [Pilate] answered and said unto them, 'Whether of the twain will ye that I release unto you?' They said, 'Barabbas'." Bach sets the text so that the angry multitude's harsh reply on the word Barabbam is a diminished seventh chord: After Bach, diminished sevenths were to feature regularly in music to evoke the uncanny or sense of impending danger. A powerful diminished seventh chord heralds the resurrection of the murdered Commendatore in the final scene of Mozart's Don Giovanni (1787). The dead man's statue comes to life and takes the Don down to Hell in one of the most chilling episodes in the entire operatic repertoire (Listen): In the early years of the 19th century, composers used the diminished seventh with increasing frequency. In "Die Stadt", one of his darkest and most melancholy songs from Schwanengesang (1828), Franz Schubert conjures "the pianistic elaboration of a diminished seventh over an octave tremolo" to convey the sinister rippling of the oars as the protagonist is rowed across a