The melody of Britten's This Little Babe is the work's unwavering focus: First, the melody is presented in unison by the chorus; then, it is presented in close imitation; it repeats a third time, with a double echo. Finally, at the culmination, the melody is played once again in rhythmic unison, but this time in slow motion with more complex harmony. The piece ends triumphantly where it began.

This movement ends with a powerful restatement of its opening material. The sense of return is forceful and decisive.

This piece distills a strong round-trip to a spare essence. The work opens with a two-note chord, repeated six times all by itself before anything else happens. The two-note chord is then merged within a more elaborate texture. Later, for a brief time, it disappears. At the end, it reasserts itself--moving at the same speed, in the same register. The piece does not retrogress all the way back to the opening's starkness: scattered other events occur; the two-notes are merged within a more complex sonority at the end. But the sense of return is strong: The two-note chord creates a clear focal point, and the end affirms this.

However, the answer is not entirely unambiguous. If you answered "Weak Round-trip", then you may have felt that the novelties at the end undermine the clarity of the return. The pattern of repetition of the two-note chord, for instance, differs. The two-note chord is never left completely alone. The concluding chord is dissonant and unresolved.

In my opinion, the novelties do not mar the identity of the return. The ending is more complex, but the two-note chord's presence is still resolute: Until the last sonority, it is always attacked on its own, without added notes. We have been introduced to the two-note motive so clearly than we can easily identify it, especially because not much else is happening. "Home" is enriched, but it is still secure. That is what marks this work as a "strong round-trip".

The Ballade ends with an allusion to its opening theme. However, the return is very brief: It sounds almost parenthetical after the extended, very tumultuous section that precedes it. Also, very unexpectedly for music of this era, the Ballade ends in a different key than it began: If you compare the two examples below, you will notice that the theme begins on a different repeated note.

If you answered "Strong Round-trip", then you clearly noticed the return of the opening melody. However, you did not give enough consideration to the fact that the return is severely curtailed. Added to the fact that the music ends in a different key, "Weak Round-trip" is a more accurate answer.

If you answered "One-Way Progression," then you may have put a lot of emphasis on the fact that the music ends in a different key than it began. If the piece were to have ended with the tumultuous music, or some new material, then the sense of "One-way Progression" would be unequivocal. However, Chopin incorporates a glance back to the opening: "Weak Round-trip" acknowledges this ambivalent retrospection.

The music ends where it began: with the same instrument (oboe) playing the same solo melody. However, the concluding solo is at a higher pitch level, and is cut off unexpectedly. (Varèse abbreviates the oboe melody so that the first movement flows more rapidly into the second.)

If you answered "Strong Round-trip," you may have felt that, in a musical language with so much suspenseful tension and dense combination of sound, the final solo acts as a "resolution," even if it is incomplete. Those perceptions are valid. However, "Weak Round-trip" is a more accurate answer, because it allows for the possibility that the melody could have returned at its original pitch level and in complete form.

If you answered "One-way Progression," you may have put particular emphasis on the fact that the melody returns in a new transposition. If a different instrument--for instance, the flute--had been playing, or if there had been more drastic transformations--for instance, a highly embellished melody--the sense of "one-way progression" would indeed have been strong. "Weak round-trip" acknowledges that the feeling of return is still palpable.

Schoenberg's song "Nacht" begins with soft, slow moving music, filled with foreboding, in the low registers of the bass clarinet, cello and piano. Gradually, the music builds in intensity and rhythmic action, culminating in a climactically loud arrival. The music then subsides, sinking lower and getting softer, until it eventually returns to its original low register, soft dynamic and slow speed. In addition, the voice is singing the same line of text. The arch-like rise from the depths and return back downwards marks this movement as a round-trip.

But which kind, "strong" or "weak"? On the basis of the arch-like trajectory of the rhythm, texture and dynamics, a good case could be made for a "strong round-trip."

However, Schoenberg disguises the ending's motivic relationship to the beginning. At the opening of Nacht, the piano opens with a three-note motive, which is imitated by the cello and bass clarinet. This motive, so clearly echoed, is the basis for the entire movement. At the end, the motive's presence is veiled: The piano replays the motive underneath the voice, but the cello and clarinet no longer imitate it exactly. Furthermore, it may take several hearings to notice the motive is spelled out by the last three chords. The music has made it back to its origin, but ambiguity intrudes. In the Piano Piece, opus 11, the return to the opening dyad is still explicit. At the end of "Nacht," the motive's presence is more nuanced. The answer "weak round-trip" better captures this equivocation.

The first movement of Berg's Four Pieces for Clarinet and Piano is an example of the ending contradicting its opening. The piece begins with a gentle, forward-moving clarinet melody--first alone, then accompanied by the piano. About mid-way through the piece, the clarinet drives into its low register with a raspy exclamation. This gesture acts almost like a curtain on the first part of the piece. From then on, the music evolves new characteristics. By the end, both clarinet and piano have become very static: The clarinet anchored on a softly repeating low note; the piano with a dense, repeating chord. There is no harmony at the beginning; at the end, the melodic motion is frozen and there is only harmony.

At the opening, the music is concentrated in the middle registers. At the end, the piece stretches between the extremes of the piano: Both the work's highest and lowest notes occur in its closing chords.

At the opening, the clarinet changes speed fluidly and unpredictably. At the close, the clarinet's rhythm is a more straightforward slowing down. Thus, the work ends in a very different way than it began.

If you answered "Weak Round-trip," then perhaps you noticed a subtle connection: The first notes of the clarinet solo are collected into the final chord. However, this is a radical transformation: What was horizontal has become vertical; what lay close together in register has been exploded in range. Also, the notes are all rearranged in space: The high point of the melody is the low point of the chord! When so much has changed, the sense of return becomes very tenuous and obscure.

Ligeti's Desordre is an example of a continuous progression that carries the music far from where it started. The work moves continuously with an unchanging fast pulse. The pitches in each hand are fixed: the seven notes of the C-Major scale in the right hand, the remaining five notes of the chromatic scale in the left. A melody, played in imitation between the hands, repeats over and over again in its entirety, rising steadily in register. At the end, the work reaches its highest peak, with both hands rising to the extreme high of the piano. There is a clear sense of transit without return.

Furthermore, the work is designed so that nothing ever happens the same way twice. The relationship between the hands becomes extremely unpredictable and complex. Ligeti expands and contracts the main melody in different ways in each hand, making them fall more and more out of alignment--and creating the disorder to which the title refers. By the end, the left hand's irregularities are magnified, twisting its original form completely out of shape. Finally, the piece ends just before the melody is about to be replayed on the same pitch with which it began--thus, a round-trip is avoided.

If you answered "Weak Round-trip," then you may have noticed an arch-like shape created by the melody's speed: While the fast pulse remains constant, the melody accelerates towards the midpoint of the piece, then relaxes back to its original speed. However, the piece doesn't end there: It continues onwards and upwards, evolving new relationships between the hands. Desordre is moving away from its origin when it concludes. Thus, "one-way progression" is a stronger answer.