The purpose of the beginning of any tonal organ composition is to establish the mode. This is understandable, because composers didn't want their performers and listeners to wonder whether the key or mode of this piece was major or minor, in C, in D, in E, in F or some other.
One way to do this is by creating an opening sentence with a clear cadence in the original key using all three main chordal functions - tonic, dominant, and subdominant, their inversions, and related chords. For example, T-II42-D65-T or T-S64-T-D56-T or T-T6-S-S6-D-D42-T6 etc.
Another way to establish the mode is to play a long tonic chord and emphasize chordal notes in the passages with runs in sixteenth notes. For example, in the mode of D minor, the notes of the tonic chord are D-F-A. Therefore, while one hand holds the tonic chord, the other plays the passages and the most frequently heard notes (at least on stronger beats) are D, F, and A.
Today's sight-reading piece is Versus I Primi Toni (p. 1) by Abraham van den Kerckhoven (ca.1618-1701) who was a Flemish organist and composer of the Baroque period. His numerous short versets and several lengthy pieces in contrapuntal manner have survived to this day.
In this verset, the long-held tonic chord lasts 7.5 measures. Later, while looking at the bass line, we can distinguish the following chords: D6-T-S-VII-III-D-S-T64-VI-S6-T64-D-T6-VII6-T.
Interestingly, at the very end there is a 4-3 suspension (counting the interval between the tenor and bass) but if you count the interval between the tenor and soprano, you get 7th-8th. Normally, 7th resolves to 6th. Therefore, it is very rare to see a final tonic chord with double third - usually we double the root of the chord in such case.
I hope you will notice these harmonic details while you play this verset.
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Drs. Vidas Pinkevicius and Ausra Motuzaite-Pinkeviciene
Organists of Vilnius University , creators of Secrets of Organ Playing.
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