There are two important legacies regarding Chopin's exclusivity in writing piano music; first is the reconstruction of existing genres by transforming their meanings and functions; second is the experimentation with harmonic function, which was strikingly original during the early nineteenth century by an equal use of diatonicism and chromaticism along with the frequent use of dissonance. For the latter, Jim Samson, a British musicologist, defined Chopin's writing as "equilibrium" of tonal function. Chopin’s harmony resulted in the weakening of tonal system that characterized late nineteenth century music in a variety of ways, including increasing level of dissonance, non-functional harmonic progressions, artificial scales, and the attenuation of the tonic-dominant polarity. The purpose of this research is to assess Samson’s statement by selecting two piano pieces by Chopin: Ballade no. 1 in G minor, Op. 23 and Barcarolle in F-sharp major, Op. 60. The research method includes historical analyses, descriptive analyses for the musical elements, and prescriptive analyses to break down the equal use of the diatonicism and the chromaticism. After detailed analysis in chapter IV, the author provides three concluding points: Chopin’s works are still under the framework of diatonicism, while the micro level shows high use of chromaticism; Chopin is consistent with tonal equilibrium throughout his early-to-late compositions; and that Chopin was the pioneer of advancing tonal harmony, he also influenced later composers (especially Liszt, Debussy, and Scriabin).