Rhythmically, Harris's music is characterized by two principal features: 1) slow, lyrical passages generally begin with long notes and gradually introduce smaller values, which eventually prevail; 2) fast, aggressive music usually features a more even distribution of note-values within phrases. He also uses asymmetrical meters, chiefly in highly rhythmic passages in fast tempo. His early works sometimes feature successions of changing meters to delineate the varying lengths of his rhythmic designs; however, ensembles, particularly orchestras, had such difficulty with these meter changes that during the mid30s he largely abandoned them, conveying his designs instead by means of phrase and articulation markings.
His treatment of phrase structure is flexible: although a passage generally begins on the first beat of the measure or with a single-note anacrusis, subsequent phrase-beginnings often overlap barlines.
The principle underlying Harris's concept of form is what he called "autogenesis". In this, a melody or harmonic design flowers from a seed motive, each phrase following the first often either launching itself from a figure in the last measure of its immediate predecessor or referring back to the seed, the aim being to produce an effect of gradual, organic growth. His music thus often unfolds in additive fashion in autogenetically-generated blocks of texture, each gradually preparing, in Beethovenian fashion, for the following through anticipation of one or more elements of the new material. Although some of his livelier music contains sharp contrasts, Harris had difficulty assimilating these into his idiosyncratic process, and they sometimes seem awkward.
Other forms and procedures the composer employed are theme and variations and fugue, the latter, in his orchestral works especially, often a hybrid fuguevaria-tion type in which the subject is repeated with a gradual accumulation of counterpoint, often of a motivic nature. For some works, he adopted a variety of ternary form (either ABA or ABC). In his hands, though, all of these otherwise standard designs are generally articulated internally through autogenetic principles.
