Despite its status as the oldest North American period-instrument ensemble, Boston Baroque (it formed in 1973 as Banchetto Musicale) proved its continuing relevance for HIP on Friday in Jordan Hall with an evening of Mozart and Beethoven. Sandwiched between two D Major symphonies—Mozart’s Haffner Symphony, K. 385, and Beethoven’s Symphony No. 2, Op. 36—came two Mozart arias featuring soprano Erin Morley. First, she thrilled us with the Queen of the Night’s first aria, “O zitt’re nicht,” from Die Zauberflöte, one not as frequently heard as the showstopper “Der Hölle rache.” Then, Morley gave a stunningly heart-wrenching rendition of the concert aria “Vorrei spiegarvi, oh Dio!” K. 418, a substitute piece Mozart composed for a Viennese production of an opera by Pasquale Anfossi. Featuring brilliant and energetic performances—both symphonic and operatic—from the orchestra, Boston Baroque called to mind 18^th-century music historian Charles Burney’s famous appellation of an “Army of Generals.”

Beginning with the Haffner, the orchestra gave every visible indication of a cohesive ensemble. Throughout the symphony’s four movements, the musicians—particularly the strings—frequently glanced to other members of the ensemble when their parts connected in some way. For instance, principal violist Jason Fisher turned once toward the violinists to his left and another time to the cellists on his right. Such physical movement not only showed these players’ careful attention to their orchestral neighbors, but also visibly highlighted musical connections between sections of the orchestra work. Seeing visual manifestations of the musical details nicely illuminated the well-known work.

Also in line with 18^th-century concert programming conventions, Boston Baroque followed with two Mozart arias by Mozart excerpted from operas and presented in concert format. In these, Erin Morley was more than up to the challenge of the extremes of tessitura and coloratura. With great precision of pitch and shimmering high notes, Morley made these arias—some of the most difficult in the Mozartian operatic repertoire—seem effortless. She scaled the heights of the Queen of the Night’s aria with ease. Yet, she proved her worth at the end of “Vorrei spiegarvi” where Mozart challenges the soprano to leap seamlessly nearly two octaves down and then immediately more than two octaves up. Morley navigated these rapid registral changes quite smoothly even at the end of a lengthy aria.

While she thrilled us with rapid coloratura and registral skill, Morley followed Mozart’s exhortation in a letter to his sister-in-law, Aloysia Lange (née Weber) for whom he composed “Vorrei spiegarvi,” to fully inhabit the character even in performance of a concert aria. Morley showed a keen sense of drama and emotional expression even in the midst of explosions of technical skill. In “O zitt’re nicht,” she portrayed movingly the Queen of the Night as she deceptively appears in Act 1: a concerned mother pleading the hero to rescue her daughter. In “Vorrei spiegarvi,” she inhabited the role of Clorinda from Anfossi’s opera, who confesses her love for a man betrothed to another. She took this to heart and at some points seemed almost in tears. Compounding this, the poignant sound of David Dickey’s oboe blended beautifully with Morley’s crystalline upper register during the moments of his solo.

A spirited performance of Beethoven’s Symphony No. 2 followed intermission. In his remarks, Pearlman asked us to set aside, to the extent we could, our knowledge of Beethoven’s later symphonies and try to approach this work as the composer’s audience did: as something deeply rooted in convention but simultaneously straining those boundaries. He also pointed out that playing Beethoven on period instruments allows us to hear with late-18^th-century ears. Beethoven pushes the authentic instruments nearly to their limits and requires the player to work much harder to execute their parts, creating a sense of tension and extreme effort. Pearlman argued that we as modern listeners can recover something of the shock and surprise of Beethoven’s audiences even in his early works when we listen in this way.

Where in the Mozart symphony, the musicians seemed at ease and comfortable enough to glance around and take in the bigger picture, here they intensely concentrated on their own parts and moved with heavy and laborious gestures. In particular, principal cellist Michael Unterman rocked his whole body back and forth as he bowed the fast movements. As with the “Haffner,” these motions communicated as much meaning as the musical sounds. We felt deeply the tension and physical effort Pearlman described.

The choice of two D Major symphonies allowed Boston Baroque to bring in paired trumpets and timpani. These augmented the winds that Mozart had already added to the Haffner including pairs of flutes and clarinets, the latter a change from his original autograph. This expanded wind section—also used by Beethoven—created colorful timbres, providing relief from the string domination of many Classical period symphonies. In each of these offerings, Boston Baroque and Erin Morley used great technical skill and evocative, dramatic motion to transport us to the time of Mozart and Beethoven as we imagined ourselves an audience hearing these works for the first time.

Michael Goetjen, a musicologist, harpsichordist, and organist whose research focuses on 18^th-century opera and the music of Mozart, teaches at MIT and BU.