A work of immense historical importance, it includes the first known chaconne and passacaglia,[1] as well as the earliest set of variations on an original theme (i.e. not a popular song, as in all earlier music).
Il secondo libro di toccate is widely regarded as a high point in Frescobaldi's oeuvre.
The composer dedicated the book to Monsignor Luigi Gallo, Bishop of Ancona and nuncio of Savoy, a skilled keyboard player who may have been one of his pupils.
First and foremost, it contains several liturgical pieces, the composer's first forays into the field of sacred keyboard music (although he did compose sacred vocal music: two collections of motets, one of which is lost, were published in late 1620s, and standalone motets survive in manuscripts; Frescobaldi would later publish a large volume of liturgical organ pieces, Fiori musicali, one of his most highly regarded and influential works).
Secondly, the book contains Frescobaldi's only known intabulation (of Jacques Arcadelt's madrigal Ancidetemi, pur), perhaps included as a homage to one of the oldest forms of keyboard music.