Monotonality
Monotonality is a theoretical concept, principally deriving from the theoretical writings of Arnold Schoenberg and Heinrich Schenker, that in any piece of tonal music only one tonic is ever present, modulations being only regions or prolongations within, or extensions of the basic tonality. == History == Schoenberg laid out his concept of monotonality in his book Structural Functions of Harmony, writing that: "According to this principle, every digression from the tonic is considered to be still within the tonality, whether directly or indirectly, closely or remotely related.