1. The just adaptation of parts to each other, in any system or combination of things, or in things, or things intended to form a connected whole; such an agreement between the different parts of a design or composition as to produce unity of effect; as, the harmony of the universe.
4. A succession of chords according to the rules of progression and modulation. The science which treats of their construction and progression. Ten thousand harps, that tuned angelic harmonies. (Milton)
harmony results from the concord of two or more strains or sounds which differ in pitch and quality. Melody denotes the pleasing alternation and variety of musical and measured sounds, as they succeed each other in a single verse or strain.