The cycle of Chopin's Preludes Op. 28 and the 2 posthumous preludes No. 25 in C Sharp Minor Op. 45 and No. 26 in A Flat Major B. 86 are based on contrasts. Contrasts of expression, dynamics, rhythm and colour, revealing romanticism in it's full element of emotional instability, but at the same time the cycle reveals a coherence which comes from the fact that the preludes have been built around the twenty-four keys, twelve major and twelve minor, chasing the ideas of fullness which are present in Bach's Well Tempered Clavier, that inspired Chopin during that winter. The fact that his musical idols were Bach and Mozart perhaps explains his classic quality ever present in his ultra-Romantic music. Chopin's first Prelude in C Major, for example, clearly mirrors the C Major Prelude of Bach's Well Tempered Clavier and on the other hand Chopin's counterpoint, which is so Bachian, revealing sometimes elements that bring back Mozart and his way of designing the melodic lines of his operas where the sopranos sing melodies as if they were being transported by the wind.