He was born in Bologna in the very year that Torelli wrote his first violin concerto, and worked there and in Darmstadt before moving to Lisbon in the mid-1730s, where he died in the service of he royal chapel. The date and place of composition of the Christmas Symphony are not known, but its style suggests that it was written before Schiassi left for Portugal.
The noble opening ‘Adagio’ is a fully-fledged movement rather than a mere introduction. It features suspensions and echo-like repetitions of whole phrases. This latter device is carried through into the ensuing ‘Allegro’, which opens with a tight four-part three-octave canon. The second idea once again introduces the musette imitation: a distinctly rustic ‘bagpipe’ theme over a drone bass, again utilising echo affects. The whole device is repeated in the rudimentary development section of the second half, and a recapitulation of the canonic opening theme closes the movement. The ‘Largo’ which follows suggests to us that Schiassi was familiar with Vivaldi’s music. It is a themeless creation of slowly changing chords which gives the keyboard continuo player the opportunity to indulge his fancy by arpeggiating the harmonic outline. It was a device used by Vivaldi in The Four Seasons and elsewhere.
Schiassi’s finale embodies the pure time-honoured Pastorale design in 12/8, complete with yet more echo effects and the obligatory drone bass. The remarkable ending, descending in dynamic from forte to piano and then to più piano, is a kind of written-out ritardando in which ever-lengthening note values rise higher and higher to a final ethereal D major chord. Could Schiassi perhaps have visualised the Angels of the Lord ascending again after imparting their joyful message?
from notes by Robert Dearling © 1999