Despite her literary activities and the social responsibilities that accumulated as she grew older, Marianna stuck to her music. By the age of sixteen she had completed at least one mass if not two, and the solo motet Ne maris ira insane. At an even younger age she must have begun the assiduous daily exercise of composition and study she described in her 1773 autobiographical letter to Padre Martini: study to which her copies of music by Caldara and Lotti bear witness. In the years from 1760 to 1768—from the age of sixteen to twenty-four—Martines appears to have been especially interested in church music. In those nine years she wrote almost all of her surviving liturgical music as well as the solo motets, which were probably intended for performance during the Mass. To this earliest phase of her career as a composer we can also assign most of her surviving keyboard sonatas and Italian arias.

Masses

We know of four masses by Marianna, all of them early. The Seconda messa in G, one of the two earliest of her dated works, was written in 1760. Her Mass in C major is undated in the autograph score, the only source currently known; but it carries the title (in a nineteenth-century hand) Messe N˚ 1. For the present we may assume that she wrote it in 1760 or earlier. The fourth and presumably the last mass bears the date July 1765, a few months after Marianna's twenty-first birthday.

As was usual in the eighteenth century, Martines broke up the texts of the mass movements into submovements, allotting some to soloists, some to chorus. Of the Masses Nos. 3 and 4, Bruce MacIntyre has written: “They show a strong Italian influence in their multimovement number format, vocal writing, use of oboes, and extended orchestral introductions.” Three of the masses (Nos. 1, 3, and 4) include a choral setting of the intonation “Gloria in excelsis Deo,” often left to the officiating priest; only in the Seconda Messa does plainchant open the Gloria, with the choir entering at “Et in terra pax.” Mass No. 1 also sets the priest's “Credo in unum Deum,” while the other three masses begin the choral setting at “Patrem omnipotentem.” All the settings of the Gloria and the Credo end with choral fugues.