“Un moto di gioia mi sento” (K. 579) — Mozart’s substitute aria for Susanna in G major
ヴォルフガング・アマデウス・モーツァルト作
Mozart’s aria for soprano “Un moto di gioia mi sento” (K. 579) was composed in Vienna in August 1789, when the composer was 33. Written as an “insertion” number for a revival of Le nozze di Figaro, it distills operatic character into a compact, radiant G-major miniature—proof that Mozart could bring dramatic truth and vocal elegance even to occasional commissions.
Background and Context
In 1789, Le nozze di Figaro (K. 492) returned to the Burgtheater in Vienna—three years after its 1786 premiere—and Mozart supplied at least two additional numbers for the revival: the rondo “Al desio di chi t’adora” (K. 577) and the present arietta “Un moto di gioia mi sento” (K. 579) [1]. These additions belong to a familiar 18th-century practice: tailoring an opera’s musical fabric to the needs (and gifts) of a specific cast, venue, and season.
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The Salzburg Mozarteum’s Köchel-Verzeichnis entry treats K. 579 explicitly as a Figaro-related insertion (No. 13a), transmitted in an autograph keyboard reduction and incorporated into the Neue Mozart-Ausgabe as appendix material to Figaro [2]. Modern reference summaries likewise describe the work as composed for the 1789 Vienna performances and place it within Act II as a substitute number [3].
For listeners, this context matters: K. 579 is not a generic concert aria designed to showcase virtuosity at any cost. Rather, it is “theatrical utility” of a high order—music shaped to sound as if it belongs inside a living drama, even when heard today in recital or anthology.
Text and Composition
K. 579 is an Italian arietta in G major, dated to August 1789 in Vienna [3]. The text begins “Un moto di gioia mi sento nel petto…,” a succinct expression of joy edged by apprehension (delight “in mezzo il timor,” “amid fear”)—an emotional duality Mozart relishes throughout his mature vocal writing.
The libretto is commonly attributed to Lorenzo Da Ponte, Mozart’s collaborator on Figaro, Don Giovanni, and Così fan tutte; IMSLP’s work entry identifies Da Ponte as librettist [3]. The piece’s status as a substitute aria also explains its afterlife: detached from the opera’s standard performing text, it circulated independently, with IMSLP noting a first publication in 1799 [3].
Musical Character
The scoring is that of a Classical opera orchestra in miniature—soprano with winds (flute, oboe, bassoon), two horns, and strings [3]. Even without the rest of Figaro, the sonority immediately places the listener in Mozart’s theatrical world, where wind colors can suggest mood shifts as vividly as harmony.
What makes K. 579 distinctive is its economy: in a brief span, Mozart frames an affect that is not simply “happy,” but poised between brightness and nervous anticipation. That blend—joy with an undertow—feels closely aligned with Susanna’s quick intelligence in Figaro, a character often forced to think several moves ahead. The aria’s charm lies less in sheer vocal display than in characterful phrasing: short-breathed gestures that can sound like excited speech, answered by orchestral commentary that keeps the emotional temperature in motion.
K. 579 deserves attention precisely because it sits slightly off the beaten path. It shows Mozart, late in the 1780s, still engaging the operatic stage not only through grand new projects, but also through finely judged “repairs” and substitutions—small forms in which his melodic tact, sense of timing, and gift for emotional ambivalence remain unmistakable [2].
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[1] Mozarteum Digital Mozart Edition (Neue Mozart-Ausgabe): editorial preface for *Le nozze di Figaro* (mentions the two new arias K. 579 and K. 577 for the 1789 revival).
[2] Salzburg Mozarteum: Köchel-Verzeichnis entry for KV 579, including source information and NMA placement as Figaro appendix (No. 13a).
[3] IMSLP work page: composition date (August 1789), key, instrumentation, first publication (1799), attribution, and note that it was composed for the 1789 Vienna *Figaro* performances as No. 13a in Act II.