Manuscript Am.B. 340, owned by the Staatsbibliothek Berlin, contains some 45 organ pieces, presumably copied by Wilhelm Karges. Of some of the compositions contained in this manuscript the original model and composer is known. Most of them remain anopnymous. What they all have in common is that (presumably) Karges adapted the compositions to make them suitable for his duties as a church organist. Most compositions contained in this manuscript are no longer than two facing pages, have a comparable length in time (three to four minutes), and some pieces have handy indications where to perform a repeat so the length of the piece can be varied if need be. Though most pieces are heavily adapted when compared to their original (if a original is known), the adaption is skillfully done and it remains beautiful music. In his adaptations Karges shows himself a composer in the literal meaning of the word.
The model for this Capriccio is the first part of Johann Jacob Froberger's fourth Fantasia (“sopra Sol, La, Re”). Karges verson deviates from the original in only a few small details. And of course the fact that the second part of Froberger's Fantasia is omitted in this Capriccio. Interesting is that on the next folio of the manuscript Karges wrote a second Capriccio, that consist of a first part composed by Karges (he writes "W.K." below the title of the piece) and a second part that is the second part of Froberger's Fantasia. Probably Karges thought Froberger's original Fantasia too long for use in service and split it up in two pieces. And in case a longer pieces was needed, he could play the one after the other and create the impression of one continuous piece.
Score available here: http://partitura.org/index.php/wilhelm-karges-johann-jacob-froberger-capriccio