The Mozarts’ concert that eventually took place at the Little Theatre, Haymarket on 21 February 1765 had originally been scheduled for 15 February, but it was postponed on account of a performance being given that evening at the King’s Theatre, Haymarket of Thomas Arne’s oratorio
Judith. This work had first been performed at a Lenten concert at the Theatre Royal, Drury Lane on Friday 27 February 1761, and the cast had comprised several of the luminaries of the London musical scene with whom Mozart would subsequently come into contact; these included the celebrated castrato Ferdinando Tenducci (whose participation had been in some doubt because his renowned profligacy had led him to debtor’s prison; he needed to secure permission from his plaintiff to take part in the performance), the renowned socialite and former courtesan Theresa Cornelys, who from 1765 was to host the fashionable Bach-Abel subscription concerts at Carlisle House, Soho Square, and, in the title role, Arne’s mistress and muse Charlotte Brent.
The libretto of Judith was written by the young Irish dramatist Isaac Bickerstaffe, who also collaborated with Arne on Thomas and Sally and Love in a Village. The plot is based on a story from the apocryphal Book of Judith, chapters 7-15, in which Judith liberates the besieged city of Bethulia from its Assyrian aggressors by courageously entering the enemy camp and beheading their general, Holofernes. Bickerstaffe may well have been familiar with Metastasio’s libretto based on the same story, La Betulia liberata, which had also been set by Reutter (Vienna, 1734), Jommelli (Venice, 1743), Bernasconi (Munich, 1754) and Holzbauer (Mannheim, 1760), and it is worth noting that Mozart himself was to set Metastasio’s text in 1771, perhaps recalling Arne’s London oratorio.
Judith’s 'Sleep, gentle cherub!' comes towards the end of the second of the oratorio’s three parts, as the heroine is lulling Holofernes to sleep before finally executing him, and it belongs to the tradition of bewitching ‘sleep’ arias typified most famously, perhaps, by Handel’s 'O sleep, why dost thou leave me?' from Semele. Arne reveals himself to be a master at evoking mood and atmosphere, the walking bass-line underpinning a serenely unfolding web of harmony.
from notes by Ian Page © 2018