De Vries' "sonata" (1987) for piano solo marks a turning-point which led to an even more important role of extra-musical influences (Schneeweisz 12). The 'sonata' itself is based on the novel "Dr. Faustus" by Thomas Mann. De Vries is also greatly inspired by the novels of Latin-American authors, especially by the works the Argentine author Jorge Luis Borges. In his works Borges creates a large variety of mysterious repeats form a constantly recurring theme. We can see a similar trend in de Vries' compositional philosophy. As it is not possible to envision entirely the effect of written music on a listener, he or she will discover new facets in a work when subsequently listening to it. It is with this that de Vries tries to play by introducing repetition and variations on musical elements, bringing him close to the philosophy of the Argentine author (Klis 390).