III lamentation he ends the piece with a single voice repeating an F three times. Froberger would often supply such works with an explanation, sometimes very detailed (see illustration), of the events that led to the composition of the piece. For instance, the Allemande, faite en passat le Rhin contains 26 numbered passages with explanation for each; the Blancrocher tombeau features a written preface in which the circumstances of the lutenist's death are recounted, etc. The structure and style of Froberger's programmatic works, as well as his allemandes, contributed to the development of the unmeasured prelude through the efforts of Louis Couperin. Polyphonic keyboard works The rest of Froberger's keyboard works may be performed on any keyboard instrument, including the organ. The toccatas are the only ones to employ free writing to some degree; the majority are strictly polyphonic. In terms of organisation, Froberger's toccatas are reminiscent of those by Michelangelo Rossi, also a student of Frescobaldi; instead of being composed of numerous brief parts, they feature a few tightly woven sections, alternating between strict polyphony and free, improvisational passages. They are usually of moderate length and the harmonic content is not dissimilar to Frescobaldi's, although Froberger's harmony favors softer, more pleasing turns (not without some notable exceptions, particularly in the two Da sonarsi alla Levatione works), and his toccatas are always more focused on the original tonality, unlike those by either Frescobaldi or Rossi. The fugal sections are present in most toccatas and are quasi-imitative and are not as strict as later 17th century fugues; when a toccata features several fugal inserts, a single motif may be used for all of them, varied rhythmically. Whereas in Frescobaldi's oeuvre the fantasia and the ricercare are markedly different genres (the fantasia being a relatively simple contrapuntal composition that expands, as it progresses, into a flurry of intense, rhythmically complex counterpoint; the ricercare being essentially a very strict contrapuntal piece with easily audible lines and somewhat archaic in terms of structure), Froberger's are practically similar. A typical Froberger ricercare or fantasia uses a single subject (with different rhythmic variations for different sections) throughout the whole piece, and the counterpoint adheres almost flawlessly to the 16th century prima pratica. Any of the standard contrapuntal devices may be used; the main subject is sometimes paired with another theme for a section or two, and there is usually a marked contrast between sections and much