Diverging and converging progressions.
In the majority of cases, diverging and converging progressions
simply consist in the gradual ascent of the three upper parts, with
the bass descending. The distance separating the bass from the
other parts is trifling at first, and grows by degrees. On the other
hand, in converging progressions, the three upper parts, at first so
far distant from the bass, gradually approach it. Sometimes these
progressions involve an increase or a decrease in tone. The
intermediate intervals are filled up by the introduction of fresh
parts as the distance widens, so that the upper parts become
doubled or trebled. In converging progressions the tripled and
doubled parts are simplified, as the duplicating instruments cease
to play. Moreover, if the harmony allows it, the group in the
middle region which remains stationary is the group to be retained,
or else the sustained note which guarantees unity in the operation.
Below, the reader will find double examples of both descriptions.
The first pair represents a diverging progression, 1. piano, in which
the human voice takes part; 2. a purely orchestral crescendo. The
second depicts two similar diverging progressions, firstly a gradual
crescendo, secondly dim., during which the strings become more
and more divided as the wind instruments cease to play. Ex. 258.
accompanies the apparition of Mlada, Ex. 259, its disappearance.
The atmosphere and colouring are weird and fanciful. The third
pair of examples forms instances of converging progressions. In
the first (Ex. 260) Princess Volkhova relates the wonders of the
sea. Then in the middle of a powerful orchestral crescendo the
Sea-King appears (Ex. 261) Both examples include a sustained
stationary chord of the diminished seventh. The handling of such
progressions requires the greatest care.
Examples:
- No. 256-257. The Tsar's Bride 102 and 107.
- No. 258-259. Mlada, Act III 12 and 19.
- No. 260-261. Sadko 105 and 119.
- Sadko 72 (cf. Ex. 112).
- " before 315.
- The Christmas Night, beginning (cf. Ex. 106).
- * No. 262. Antar, end of 3rd movement.
Note. A sustained note between the diverging parts does not
always allow the empty space to be more completely filled up.
Example:
- No. 263. The Golden Cockerel, before 106.
