The role of the double bass in Per Questa Bella Mano seems to represents the tender beloved figure, to whom the bass singer addresses his desire.
While Mozart may embody the Wanderer tradition of Goethe, it is more likely that this aria with anonymous Italian text (rather than German) is in the tradition of opera buffa.
The Viennese bass was gamba shaped – falling shoulders and flat back, with the top of the back curved up. The strings were tuned F A D F# A. Both Mozart’s and Müller’s arias are in the key of D major, which is extremely idiomatic for this tuning. The strings were traditionally made of gut, and the three inner strings were relatively loose in comparison to the two outer strings. In such a context, A- D- F# was an advantage to fast arpeggios and double stops, creating harmonic support. Tonight, though, the bass is tuned in fourths in solo tuning, meaning one step above orchestral tuning (F#- B- E- A instead of E- A- D- G). The solo tuning was created in order to tighten the gut strings in a solo situation, hence creating a rather bright sound for the bass. The bassist’s part would therefore be written in C major, so that the sounding pitches are still in D major. Some advantages to solo tuning include better bow-to-string response, easier fingerings and clarity of harmonics and open strings. Today steel strings are made exclusively for solo or orchestral tuning. Some claim that the additional tension of solo strings caused by their higher pitch creates a brighter sound and better projection; however, as this tension is already taken into consideration when the solo strings are made, that claim is debatable. The advantage for the bassist of choosing between the two tuning systems is that some of the repertoire requires a definite scalar choice, which might work better in one tuning than the other.
Per questa bella mano By this lovely hand
Per questa bella mano By this lovely hand,
Per questi vaghi rai By these beautiful eyes,
Giuro, mio ben, che mai I vow, my dearest, that never
Non amerò che te. Will I love another but you.
L’aure, le piante, i sassi, The breezes, the plants, the rocks,
Che i miei sospir ben sanno, Which well know my sighs,
A te qual sia diranno Will tell you of
La mia costante fè. My constant loyalty.
Volgi lieti, o fieri sguardi, Look brighter, oh stern visage,
Dimmi pur che m’odi o m’ami! And tell me whether you despite me or love me!
Sempre acceso ai dolci dardi, I am always enflamed by your sweet darts,
Sempre tuo vo’ cho mi chiami, I always want you to call me yours,
Ne cangiar puo terra o cielo Neither heaven nor earth could alter
Qua desio che vive in me. That desire that lives in me.
 Mozart’s last complete opera buffa, Cosi Fan Tutte, was composed in 1790.
Wolfgang Amadeus Mozart (1756–1791): Per Questa Bella Mano, Aria for Bass, Obligato Double Bass and Orchestra, K. 612 (1791)
Darnell Ishmel – Bass-Baritone, Ron Merhavi – Double Bass, Chris Hill – Conductor, The "M" Players; Ron Merhavi's Second Dissertation Recital: McIntosh Theater, University of Michigan, Ann Arbor 17.3.2004