The herewith presented Theory of Tonality allows an analytic approach to compositions, which where hitherto not or hardly accessible for tonal itemization. The discovery of a symmetry, which is representative with regard to tonal phenomena, led to the develpment of radically new analytic method. It allows amongst others to unveil the tonal paths in enigmatic harmonies of the romantic period, in Debussy¿s pentatonic opera. Futhermore, the horizon is surprisingly extended when dealing with the patterns of classical harmonics. The increase of analytic precision motivates to contemplate common patterns of perception and permises of contemporary techniques of composing.