Unlike other collections of preludes, such as those of Bach and Chopin, Debussy’s does not follow a strict pattern of key signatures, However, there is a strong tonal relationship between the preludes in the order they have been published and Debussy and other pianists who gave early performances of the works played them in groups of three or four preludes. Each of the 24 Prelude has a descriptive title at the end of the piece. Book Two includes 12 Preludes. Durand/Allans/EMI Edition.