in general, denotes an assemblage or chain of principles and conclusions, or the whole of any doctrine, the several parts of which are bound together, and follow or depend on each other; in which sense we say a system of philosophy, a system of divinity, &c. The word is formed from the Greek σύστημα, composition.

**System**, in Music, signifies an exposition of all the sounds employed in composition, considered theoretically and practically, melodically and harmonically. The ancient Greek melodic system was divided into tetrachords; the modern melodic and harmonic system is divided into octaves. The Guidonian system was divided into hexachords. The most modern system of harmony, which originated in the sixteenth, seventeenth, and eighteenth centuries, is founded upon a system of tonality different from that employed prior to these periods, as will be shown under the article **TONALITY**. For some account of harmonic systems, see **Music**.