While his operatic ventures often took him on long journeys abroad, throughout his life Vivaldi centred on one place of employment: the Ospedalle dela Pietà, an institution for foundlings which, in common with its three other Venetian counterparts, placed a strong emphasis on musical education. He was first appointed as "maestro di violonó" in 1703, and though he was later raised to the rank of "maestro de' concerti", he was never given the most coveted post of "maestro di coro". Indeed, it seems that he was not entirely popular with the governors of the Pietà, for it was unusual for the renewal of his contract to pass unchallenged.
Much of Vivaldi's sacred music was written for the Pietà, whose chapel with choir galleries on either side must have suggested the antiphonal effects (a traditional Venetian feature) found in some of his works. Little of it can be dated exactly, but there appear to be three probable periods of activity in this field. The first of these was caused by the departure from the staff of the Pietà of the "maestro di coro", Francesco Gasparini. Although only granted temporary leave in 1713, he never returned, and Vivaldi must have filled in during his absense, for in June 1715 he was awarded an extra payment of 50 ducats for "an entire Mass, a Vespers, an Oratorio, more than 30 motets and other works". It Was some years before a replacement for Gasparini was found, and the duties, many of which Vivaldi must have taken over, were exacting, and included the provision of at least two masses and vespers a year and two motets a month. This period includes his only surviving oratorio, Juditha Triumphans, RV 644 (1716): a showpiece in operatic style for the girls of the conservatoire, employing highly elaborate and colourful orchestration.
On two other occasions while Vivaldi was employed at the Pietà the choir of the conservatoire found itself without a director. The first of these was in 1726 when Gasparini's successor, the rather undistinguished C. P. Grua, died, leavong Vivaldi as the likely stop-gap to provide choral music for the Easter festival. The second began in 1737 and lasted almost two years, providing Vivaldi with a final incentive to compose sacred vocal works.
Magnificat RV 611
The Magnificat exists in the Turin manuscripts in three different versions. Firstly as a work for single choir and orchestra (RV 610); it was then altered into a larger double-choir work (RV 610a), each choir having its own orchestra. Here seven of the nine movements are for chorus, including one, "Sicut locutus", for three-part chorus (without tenors) with two independent oboe parts.
The final version of the Magnificat (RV 611) takes over six movements from 610a, the others being replaced by live solo arias, each one bearing the name of its intended performer. Of the remaining sections, "Et Misericordia" is notable for its depth of harmonic interest and expressive use of the rising intervals of a minor sixth and a major seventh, while "Deposuit potentes" comprises vigorious unison writing. The five new arias appear from their musical style to date from the later 1720's (probably from the time just following C. P. Grua's death), and were written for five of the girls at the Pietà: Apollonia, la Bolognesa, Chiaretta, Ambrosina and Albetta. A light-hearted poem written around 1730 describes the conservatoire's leading pupils, and tells that Apollonia had a clear soprano voice and was an expert at both pathetic and lively singing. Maria la Bolognesa had a pleasing voice but tended to inaccuracy, while Ambrosina had a deep voice whose tone sounded like that of a tenor, and indeed her aria is written in the tenor clef.
The most interesting change in this final version of the Magnificat is that the text of the original sigle movement "Et exultavit", first set for successive soprano, alto and tenor solos with a brief choral interjection, is split into three independent solo arias with more extended musical settings. All five arias display styllistic features typical of Vivaldi's operatic music, such as the falling chromaticism in the accompaniment of "Quia respexit" and the incisive syncopations and so-called "Lombard" rhythms (semiquaver-dotted quaver) of "Esurientes". The addition of this florid virtuosic writing to the more solid choral movements makes this Magnificat a splendid example not only of the way in which Vivaldi could adapt his own works, but also of the variety inherent in so much of his best music.
Gloria RV 589
Since its first modern revival in Siena in 1939, this work has become by far the most popular of Vivaldi's choral works. In common with many of his other settings of texts from the Ordinary of the Mass, it was not intended as part od a complete mass, although one such work (RV 586) does survive.
The Gloria probably dates from around 1715 and has a typically extrovert opening. The ritornello introduces a unisson theme in D major centring around the tonic chord, and orchestral colour is provided by the addition of a trumpet and an oboe to the basic string orchestra. The second movement, "Et in terra pax hominibus", is an expressive B minor andante with a gently pulsating bass over which vocal layers gradually build up with considerable harmonic intensity. Following the lively duet for two sopranos, "Laudamus Te", the brief chordal "Gratias agimus tibi" introduces a contrasting imitative movement, "Propter magnam gloriam". The reflective mood returns for "Domine Deus, Rex coelestis", where a lilting soprano solo alternating with a solo oboe or violin is accompanied by the continuo alone. This accompanimental texture is again used for the alto solo in "Domine Deus, Agnus Dei" which is interrupted by incisive phrases for the full chorus and strings.
In "Quoniam tu solus sanctus", music from the first movement returns in an abbreviated form, and this re-use of opening material at the end of a work to give a sense of unity is common in Vivaldi's sacred works, and even occurs in one of his operas (the pasticcio Rosmira fedele, RV 731).
The final double fugue "Cum Sancto Spiritu" has an interesting history. Vivaldi was an inveterate borrower, though normally from his own works, and this movement is based on the finale of another Gloria to be found in the Turin manuscripts: one by G. M. Ruggieri written in 1708. This was borrowed by Vivaldi for an earlier Gloria, RV 588, reducing the forces from two choirs ans orchestras to one and eliminating the second viola part. Here it is again slightly altered, although its basic shape remains constant.