In Maurice Ravel’s Bolero, a fixed rhythmic pattern—first played by the snare drum—anchors the entire composition.

In this excerpt from Steve Reich’s Music for Large Ensemble, the evolving texture grows out of an underlying rhythmic pattern.

A rhythmic motive may be a key identifying feature. The opening of Beethoven’s Symphony No. 5 consists of music’s most famous rhythmic motives: “three dots and a dash.”

In this excerpt, the rhythmic motive is passed around the orchestra:

Lalo Schifrin’s theme for Mission Impossible contains a rhythmic motive consisting of “two dots and a dash.” A fixed pattern, or ostinato, underlies the Mission Impossible theme, also contributing to its identity.

Bruckner maintains the contour but varies the details in this soft statement by the French Horn:

This climactic statement by the brass includes one extra push upward:

Let’s recall the theme Nicolo Paganini’s Caprice No. 24 for solo violin, this time in a playful orchestration by Witold Lutoslawski.

One of the identifiable features of Paganin’s theme is that its contour rollicks up and down predictably. In this variation, Lutoslawski scrubs away the melodic and rhythmic details, leaving only the contour. Paganini’s theme is recognizable by its shape.

Often, melodies can be analyzed as being made up of one or more motives. The opening theme of Ludwig van Beethoven’s Sonata in E, Opus 109 is made of a short-long motive. The motive alternates direction, first going up and then going down.

The opening theme of Dmitri Shostakovich’s Symphony No. 5 is similar: It is also made of a short-long motive. Whereas Beethoven’s motive flipped up and down in quick alternation, Shostakovich’s motive is repeated before changing direction.

The slow movement of Felix Mendelssohn’s Cello Sonata No. 2 opens with a long harmonic progression played by the piano alone.

Later, the progression is replayed in its entirety. This time, the cello adds a ruminative melodic line.

Similarly, Richard Strauss’ song Morgen similarly opens with an extended harmonic progression, played by the piano alone. As the voice concludes her first phrase, the progression is replayed, this time with a soaring vocal line. Once again, the harmonic progression is essential to the music’s identity. As you listen to the excerpt, you will notice that the progression deviates at the end: Rather than closing conclusively, Strauss substitutes a suspensive chord that leads to the next section.

Whereas one pitch or one rhythmic attack is not enough to create a motive, a harmonic motif can be created by just one chord. Richard Wagner’s monumental opera Tristan und Isolde is unified by a single harmony—the so-called “Tristan chord.” It reappears obsessively throughout the four-hour drama, constantly resolving in different ways.

Wagner saves one of the most poignant resolutions for the final one.

In his Chamber Symphony, opus 9, Schoenberg uses a non-traditional chord as a structural signpost, heralding the beginning of new sections.

The final time this chord appears, Schoenberg turns it upside down:

Here is a sampling of music in Major.

Here is a sampling of music in minor.

Bela Bartok’s Chromatic Invention from Mikokosmos, Book III is based on a more clustered collection of notes.

In Krystof Penderecki’s Threnody for the Victims of Hiroshima, the pitches are even more densely packed.

Later in the movement, the sound of the sleigh bells alludes to the main theme.

The opening theme of the second movement of Maurice Ravel’s String Quartet is played by a striking texture of plucked strings.

Later in the movement, just the sound of plucked strings is enough to evoke the opening theme. Further hints of the theme’s identity are sprinkled into the texture, until the theme returns with full force.

Twentieth century composers were particularly adventurous about exploring new sounds and instrumental combinations. For instance, John Cage invented the prepared piano by inserting screws, erasers, thumb-tacks and other objects inside the piano. The prepared piano’s unique timbre is part and parcel of the identity of this work.