The Boston Early Music Festival Orchestra has been busy with this year’s festival opera, Handel’s “Almira,” but Thursday night at Jordan Hall, it focused on orchestral cosmogony. “The Birth of the Orchestra” provided snapshots of the turn of the 18th century, when that ensemble began to come into its own in European music.
Thursday’s orchestra was small by philharmonic-sized standards: strings, three reeds, occasional percussion, continuo keyboards. Nevertheless, the repertoire was designed to highlight instrumental mass. An Overture and Sonata from George Frideric Handel’s 1707 “Il Trionfo del Tempo e del Disinganno,” for instance, exploited concerto grosso practice, periodically shrinking the discourse down to primary-color solos — paired violins (orchestra director Robert Mealy and Cynthia Roberts), paired oboes (Kathryn Montoya and Gonzalo Ruiz), or a burbling organ (Avi Stein) — in order to amplify the punch of the full band charging back in. The Overture from Handel’s 1709 “Agrippina” decadently escalated such contrasts, coupling big/small, loud/soft switchbacks in dizzyingly abrupt shifts of tempo and rhythm.