Symmetry. Each of the three hexachords that comprise this block can be thought of as nearly symmetrical. In the prime form representation, (012346), the axis of near-symmetry is the 3, and the only unpartnered tone is the 1. The unpartnered tone in the first hexachord (B) can be thought of as seeking an implied D♯, the arrival of which would turn the near-symmetry into a true symmetry. Similarly, the unpartnered tone in the second hexachord (A) may be thought of as yearning toward C♯. These transformational urges are satisfied in the final hexachord, which contains both C♯ and D♯ (presented by Stravinsky as the outer voices of the chord).