Frescobaldi's final publication of completely new material, Fiori Musicali, appeared in 1635 and was widely reproduced over the next century. Interestingly, the surviving copies show little sign of use, suggesting that the works were employed for private study more often than for performance. Frescobaldi hoped for the widest possible use; almost every item in the collection requires only three octaves, to accommodate the limitations of newer organs in Italy at the time (older instruments often had a four-octave range). In his preface, Frescobaldi suggests that he intends the collection for personal perusal and self-education rather than being a spinoff of music he composed specifically to be performed at St. Mark's Basilica, where Frescobaldi was employed. One detail of interest to scholars is that the first Kyrie in the Messa della Madonna contains what seems to be a slur; if it's genuine, rather than a misplaced tie, it is the first slur in the history of printed keyboard music.

Frescobaldi wanted players to read the music from an open score, so each of the four melodic lines is printed on its own staff to emphasize the up-to-date part-writing. Still, he goes back to plainchant for some source material. The Kyrie verses of the three masses are based, respectively, on the plainchant settings "Orbis factor," "Cunctipotens Genitor Deus," and "Cum jubilo," although in simplified versions.

In his preface, Frescobaldi declares that he hopes these pieces will be useful to organists to play at Mass and Vespers. He gives performers great liberty, including the power to make cuts: "They may bring the Canzonas to a full close at any Cadence, & likewise the Ricercars also, should the composition otherwise like to be too long." Presumably he means too long for use in service, rather than too long for the organist's taste.

The collection falls into three large divisions. First, the Messa della Domenica contains 17 pieces, beginning with a toccata, continuing with 11 Kyrie and Christe movements, and concluding with a pair of canzons bookending a ricercar and a toccata. Second is the Messa delli Apostoli, 16 pieces in basically the same pattern, except with a larger group of non-liturgical movements after the Kyries and Christes. Finally, the Messa della Madonna includes 14 pieces, of which only six are Kyries and Christes; a bergamasca and a capriccio close the series. Although tempo is largely left to the performer, Frescobaldi does suggest beginning the toccatas slowly and then making them quicker.

© James Reel, All Music Guide