Who Wrote Froberger's Toccata XX? Questions of Author Attribution in Early Keyboard Music

In early solo instrumental music, the links between composers' names and their works are easily broken. A composition may be transmitted without any name attached, or with an incorrect one. As a case study, the transmission of a work known as Toccata XX by Johann Jacob Froberger, and widely accepted in the canon of his keyboard works, is examined. This work is included in eight early sources, none of them central to Froberger. In four of those it appears anonymously, whereas in the other four it is credited to three different composers. Since the evidence is not sufficient to attribute it securely to anyone among them, we should consider Toccata XX a work of uncertain authorship, perhaps "from the school of Froberger."