Music Composition: The Ordering of Pitched Sounds in Time and Space.
It’s really very simple… At its most fundamental level pitch relationships are referred to as intervals; their specific occurrence in musical time is determined by rhythm, a concept that embraces all durational aspects of music. Rhythm in turn may or may not be regulated by metre. In metrically organized rhythm, recurring patterns of accented and unaccented “beats” furnish a durational substructure that necessarily affects all the other elements of composition, including the nature of melody, harmony, and texture. Get it?