In his Third String Quartet, Bartók often spins out melodic lines from brief motives, and the spinning-out frequently takes the form of motivic chains – a linkage of two motives where the last note or notes of the first become the first note or notes of the next, and the two are related by one of the four traditional serial transformations: transposition, inversion, retrograde, and retrograde inversion. There are thus four kinds of motivic chains: transposition (T) chains, inversion (I) chains, retrograde (R) chains, and retrograde inversion (RI) chains. Chains of this kind, especially I-chains and RI-chains, shape not only the melodic lines of the quartet but also its harmonic progressions. They lend the quartet a quasi-serial organization at a time when the composer thought he was ‘approaching a species of twelve-tone music’.