Credidi propter quod RV605, a setting of Psalm 115 (116), which is the fifth and last Psalm sung at the Vespers of several feasts, is from start to finish in the stile antico. It is mostly a simple contrafactum (retexted version) of an anonymous Lauda Jerusalem in C major for five voices and continuo (RVAnh.35) preserved in Vivaldi’s collection. Since the latter Psalm has ten verses and the Credidi propter quod has nine, it is almost possible to make the textual substitutions on a straight-forward verse-for-verse basis (Vivaldi eliminates the small numerical discrepancy by treating each semiverse in verse 5 of the Credidi as if it were a full verse). In one case, however, simple retexting was impossible because of the very overt word-painting used in the model. For verse 4 of the Lauda Jerusalem its anonymous composer chose to illustrate the idea of the Lord’s word running very swiftly (‘velociter currit sermo ejus’) with fast-moving figures that would have made no sense in their new context. Vivaldi therefore composed his own setting for the matching verse (‘Calicem salutaris …’); it is slightly more ‘modern’ in flavour than its surroundings, but considerably more expressive.
Probably because at the first performance he had an orchestra to hand that he did not wish to leave idle, Vivaldi prescribed doubling by strings for all the upper parts. Characteristically for the period, the soprano is doubled by the second violin, while the alto is doubled an octave higher by the first violin. This expansion of the total compass prompted Vivaldi to make some small redistribution of material between the parts, with benefit to clarity and sonority. No one would claim the Credidi—whomever we choose to regard as its true composer—as a masterwork, but it has a sombre grandeur and represents an important side of the church music of Vivaldi’s time.
from notes by Michael Talbot © 1997