Mark Swartzentruber, Debussy Toccata

Wikipedia: Given that Debussy's music is apparently so concerned with mood and colour, one may be surprised to discover that, according to one author, many of his greatest works appear to have been structured around mathematical models even while using an apparent classical structure such as sonata form. Howat suggests that some of Debussy's pieces can be divided into sections that reflect the goldenratio, frequently by using the numbers of the standard Fibonacci sequence