Giovan Battista Ferrini was Roman and his birthdate estimated around 1601; he worked chiefly as an organist there, from 1619 at S. Luigi dei Francesi and, from 1623 to 1653, the "Chiesa Nuova" in Valicella. Ferrini then retired and lived another two decades, dying in 1674; in these years he traveled widely throughout Italy, making personal appearances at various churches and participating in civic music-making and special events. None of his extant music appears to be sacred, and it appears his colleagues knew Ferrini primarily as a composer of harpsichord music, judging from his nickname "della Spinetta." Apart from short examples published in theoretical works, Ferrini's music never appeared in print during, or even immediately after, his lifetime. However, Ferrini's music was widely distributed in manuscript, with some dances turning up as far away as England; Ferrini was quite famous in his day, and his music praised by Athanasius Kircher, among others. From Kircher we learn that Ferrini may have written vocal music, as well, but none of that appears to exist, and Pitoni indicates that some of Ferrini's music was also instrumentally played. The main source for Ferrini's compositions is a manuscript in the Vatican Apostolic Library that contains 12 pieces with numerous concordances elsewhere. The presence of several Ferrini pieces in another Vatican manuscript, Chigi Q.IV 25, suggests that he may have been of the school of musicians clustered around Girolamo Frescobaldi, as Frescobaldi's students compiled this manuscript, although Ferrini may simply have been an outsider whose work was admired by them. Perhaps his birthdate was somewhat earlier and he was more of a contemporary of Frescobaldi. Nevertheless, Ferrini was familiar with the approach to variation form that we associate with Frescobaldi, as heard in his Partite sopra l'Aria di Fiorenza and Capriccio fatto sopra il Cucchù. This last-named work is a highly complex set of polyphonic variations where a two-note "cuckoo" figure both intersects, overlaps, and interrupts the texture at unpredictable points in the piece; it is one of the most startlingly experimental keyboard pieces of the early seventeenth century.