In his first period of sacred vocal music composition at the Pietà, Vivaldi pioneered the practice of inserting short solo motets (introduzioni) before major choral items such as the Gloria in the Mass or the Dixit Dominus at Vespers. The present introduzione, which belongs to a large group of Vivaldian compositions with a connection to the feast of St Lawrence Martyr, was in all probability composed in the 1720s or early 1730s for an institution other than the Pietà, and shows that Vivaldi was keen to extend the use of this newly invented genre. Since its key is B flat major, it is highly unlikely that it was designed to introduce one of the extant Vivaldi settings of the Gloria (RV588 and RV589), both of which are in D major. Perhaps it was linked to a setting, presumably by Vivaldi himself, in B flat major that was a partner to the surviving Kyrie in G minor, RV587. Although RV637 is not itself laid out for two cori, a reference to ‘organi’ (in the plural) in the autograph score implies that it was intended for performance in circumstances where the ensemble was divided.
From a close examination of the manuscript, it appears that the work originally consisted of two movements: an aria and a recitative. The first describes the soul’s combat with the powers of darkness, armed with faith, while the second calls on the aid of St Lawrence in the struggle. The word ‘Gloriam’ (accusative of ‘Gloria’) appears in the last line of the recitative as a ‘pre-echo’ of the first word of the main work. At a later stage, however, Vivaldi decided to lengthen RV637 by adding a prayer to the saint in the form of a slow aria. This caused him to replace ‘Gloriam’ (now made redundant) by ‘laeta’. The gentle lyricism of the added aria provides an effective contrast to the blood and thunder of the opening one.
from notes by Michael Talbot © 2002