The Phrygian cadence

The minor mode’s own half close: the subdominant in first inversion falls a half step in the bass onto the dominant — the sixth degree to the fifth — while an upper voice rises the other half step from the tonic to the leading tone. Two semitones closing in contrary motion give the cadence its unmistakable colour; the name remembers the Phrygian mode, whose scale closes with exactly this half-step fall onto the final.

Minor’s answer to the ordinary half cadence, and by far the most common way a minor-key phrase pauses on the dominant rather than closing on the tonic. It ends on V exactly as the plain half cadence does and carries the same question-mark function, but the falling half step in the bass gives it a weight the plain form lacks — why Baroque slow movements lean on it for the close of an interior phrase or a whole movement. The two half steps are compact enough to appear wherever voices are free to move toward the dominant by step.

• Using the subdominant in root position rather than first inversion, which erases the half-step fall in the bass that gives the cadence its name.
• Leaving the dominant’s third unraised, so the upper voice never reaches the leading tone and the cadence loses its defining half-step rise.
• Doubling the leading tone in the closing dominant chord.
• Letting a single voice carry the melodic path from the natural sixth degree up to the raised seventh, producing the augmented second the two-voice contrary motion exists to avoid.

• Johann Joseph Fux, Gradus ad Parnassum (1725), Liber secundus, the cadences proper to each mode — The E-mode close — half step falling onto the final — is the ancestor the minor-key formula keeps.
• Johann Sebastian Bach, The four-part chorales (1750), Minor-key chorale closes, passim — The repertoire’s standard interior close in minor: iv6 onto the raised dominant.