The Lassus-Fantasy for orchestra is based on a short two-part Fantasia by Orlando di Lasso, written in the typical contrapuntal style of the period. It was written not only to commemorate the 400th anniversary of Lasso's death but also as an homage to a composer who had an extraordinary ability to evoke a maximum of expression with a minimum of means. The compositional challenge of this piece was to use a fairly large modern orchestra with all its possibilities, but at the same time to derive everything in the piece from the musical material given by di Lasso.

As in the original Fantasia, there is a slow introduction paired with a virtuoso second part. Original Lassus-quotes are threaded consecutively like a "silver line" through the first part, being treated as strange or foreign entities against the background of an otherwise "new music" orchestral texture. In the second part the "old material" is assimilated into the contemporary style; it actually restricts itself to one remaining Lassus-motive (the beginning of the Fantasia: "a, g, f, b-flat, a"), which functions as a recurring ritornello.

The overall form is probably best described as being somewhere between a passacaglia and a sort of static rondo; the music never really leaves the realm of the ritornelli; these, however, as in a passacaglia, always vary. The basic mode of the piece remains fairly stable throughout, and in spite of the relatively fast tempo towards the end, the gesture remains majestically striding.