Vivaldi's "Nisi Dominus" (RV 608) is in G minor and is originally scored for solo voice, viola d'amore, a small string group, and continuo. It is one of two settings by Vivaldi of the Nisi dominus (Psalm 126 or 127) text. The other, RV 803, only recently authenticated, dates from the late 1730s, but RV 608 is an early work, perhaps composed for the Venetian girls' orphanage that employed the composer in the 1710s. In nine short sections, the work is remarkable for its variety; it supports the conclusion that the obscurity of Vivaldi's vocal music is due more to historical accident than to any lack of quality. Though it has been sung by male countertenors, the vocal part would probably have been composed for a female alto if the work indeed originated during Vivaldi's tenure at the orphanage.

It is the variety of instrumental accompaniments, as vivid as those of any Baroque opera, that brings the work to life. The third section, "Surgite" ("It is vain for you to rise up early, to sit up late, to eat the bread of sorrows") is an accompanied recitative with vigorous illustrations of both the early riser and the bread of sorrows in the orchestral strings. The following "Cum dederit" ("When He shall give sleep...") is a masterful chromatic siciliana that ranks among the most alluring Baroque depictions of sleep, complete with string mutes. "Sicut sagittae" ("Like arrows in the hand of a mighty man...") offers still more operatic text-painting, with stabbing unisons dominating the texture. The "Gloria" section replaces the usual festive mood with a meditative, dark setting, and the other movements are similarly original. Some have simple continuo accompaniment, while others have a viola d'amore part (perhaps written for Vivaldi's own use, for he was a virtuoso player on the instrument) taking on a concerto-like role. It is perhaps only the presence of that unusual instrument that has kept this lovely work from the pinnacles of popularity where some of Vivaldi's other compositions reside.

Source: AllMusic (https://www.allmusic.com/composition/nisi-dominus-psal m-126-for-voice-viola-damore-strings-continuo-in-g-mino r-rv-608-mc0002362213/excerpt).

Although originally composed for Voice (Alto), Strings & Continuo, I created this arrangement of "Sicut erat in principio [...]" (As it was in the beginning) from "Gloria Patri et Filio [...]" (glory to father and son) for Flute & Piano.