How did Girolamo Frescobaldi use fugal writing in Fiori musicali?

In his 1635 collection Fiori musicali ("Musical Flowers"), Girolamo Frescobaldi utilized fugal writing to create organ music specifically intended for liturgical use.12

Within this work, he employed fugal techniques in two primary ways:

• Imitative cantus firmus pieces: These compositions are based on a preexisting melody, which is then developed through imitative counterpoint.2
• Substantial fugues: Frescobaldi included significant, self-contained fugal movements, such as the Recercar dopo il Credo ("Ricercare After the Credo") and the Canzon post il comune ("Canzona After the Communion").2

These pieces reflect Frescobaldi's broader approach to composition, where he carefully subordinated his dramatic inventiveness and bold use of chromaticism to logical, effective construction. His work in this period helped advance the principle of monothematic writing, which moved away from the earlier practice of presenting multiple themes in rapid succession.1