Calzabigi’S libretto breaks tradition with the high baroque formulas of Metastasio by presenting only three principal characters and focusing the preponderance of attention on one of these — Orfeo. The opera is extremely short by 18th-century standards and is entirely devoid of subplots. The chorus is drawn into prominence and the opera contains precious few full-blown arias.

Gluck composed practically nothing other than opera and ballet, and until Orfeo had written rather typical Italian opera seria. Yet in Orfeo, given the parameters of Calzabigi’s libretto, he achieves an elegant simplicity and directness whereby he vividly represents the passions of one man — a superman, a demigod yes; but a man nonetheless.

Guadagni, who premiered the role of Orfeo, was uniquely suited to portray that man. Unlike most of his fellow castrati, he had experience with the more naturalistic characterizations of opera buffo and training under the famed British tragedian David Garrick. This background coupled with the exceptional vocal training afforded castrati and Gluck’s notoriously torturous coaching prepared his widely acclaimed performance of Orfeo. With Gluck and Calzabigi, he represented Orfeo as a person of great nobility who, nonetheless, exhibits human frailty and deeply moving human passion.

Thus we see in Orfeo a glimmer of the grand opera which was to come. It is perhaps for this reason that Orfeo is one of the oldest opera in the world’s standard operatic repertoire. After its premier in Vienna in 1762, it was played throughout Europe by Guadagni and, in a transposed version, by the soprano castrato Millico.

From the original Italian score and Gluck’s expanded 1774 French version, Berlioz prepared an amalgamated version for the celebrated French mezzo Pauline Viardot in 1859. Saint-Saëns edited this version for publication in 1890. Then, Ricordi published it with an Italian text, and it is this inconceivably twisted version which has been performed most commonly in opera houses to this day.

This evening’s performance is given much as Gluck first presented it — from the piano, with Guadagni singing, before a gathering of friends and patrons. Stage actions are only hinted at, but may be more fully imagined at the direction of the libretto. A second, backstage orchestra is suggested by the softest notes of the piano. The overture and final ballet have been omitted for lack of instruments and dancers.