Lo Frate 'nnamorato or The Enamoured Brother was Pergolesi's first operatic comedy. It was premiered in 1732 at the Teatro dei Fiorientini in Naples and met with immediate success.
The plot concerns love triangles and mistaken identity. It is the usual Neapolitan comedy fare of the time. Ascanio is adopted. He loves his adopted sister Lugrezia, but thinks it is simply brotherly love. Marcaniello (Lugrezia's father) has promised her to Carlo. In return, Carlo promises to marry his two nieces to old man Marcaniello and his eldest son Don Pietro. However, the three girls love Ascanio and do not consent to the arranged marriages. Frustrated, Don Pietro asks his brother Ascanio, to plead with the sisters.
The sisters confess their love for Ascanio and Don Pietro takes his brother to task. Ascanio, the enamoured brother of the title, confesses that he loves all three women and cannot choose between them. Don Pietro is infuriated and wounds his brother in a duel. As Carlo treats Ascanio's wound, he recognises a birthmark and realises Ascanio is his long lost nephew and brother of the sisters. This explains Ascanio's affection for the girls. Ascanio declares his love for Lugrezia and the unsuccessful suitors confess themselves defeated.
The opera was recorded live at La Scala in 1989. The accompanying booklet has notes in Italian, English, French and German. The libretto is included and translated into those languages. The notes say that all the voice parts are at their original pitch, meaning a woman sings the serious role of Ascanio, which would have originally been sung by a castrato. The Orchestra del Teatro alla Scala probably play modern instruments. Keeping to the original score only a string orchestra is used, except for flute on one aria, and we are told that baroque performing traditions were respected. The booklet also says that some cuts were made to reduce the opera to an acceptable length.
I am not convinced that reducing operas to an acceptable length was a valid argument in 1989, when people knew what to expect from a baroque opera. Lo frate 'nnamorato is recorded over 3 CDs and stands at 2 hours 41 minutes. Each CD contains one act and the third act is 36 minutes long.