At a recent rehearsal with my string quartet, we had barely begun the slow movement of Beethoven’s Op. 59, No. 1 when we stopped playing and started debating. One bar near the end of the mournful theme was marked decrescendo. So far, so clear: Play more quietly. Two bars later came a crescendo — the opposite. But nestled between them was a single word, written in Italian under the staff: morendo, or “dying.”

Beethoven already had us fading the volume. He could have simply extended the hairpin, that greater-than sign composers use to indicate a decrescendo. So why reach for a word? He seemed to be after something more than a drop in volume, a sense of life draining out of the phrase. But did he mean for the pulse to slow, too? Or just for the sound to grow thinner, paler, more frail?

Morendo is a comparatively straightforward example of what musicologists call paratext: words used alongside musical notation. Musicians routinely wrestle with interpreting oblique, ambiguous and outright surreal markings as they try to bring a composer’s idea to life. The most famous example is Satie, whose performance indications skirt the boundary between mysticism and Dada: “Light as an egg” and “Like a nightingale with a toothache.” Percy Grainger asked for one passage to be played “with pioneering keeping on-ness.”

Others are more poetic, such as the Icelandic composer Anna Thorvaldsdottir, who offers this image in the preface to some of her scores: “When you see a long sustained pitch, think of it as a fragile flower that you need to carry in your hands and walk the distance on a thin rope without dropping it or falling.”

In an interview, Jan Grüning, the Ariel Quartet’s violist, said that linguistic cues are often more concerned with instilling an attitude in the performer than with specific musical gestures. Sure, he said, a metaphor like morendo might inspire “a heaviness, a slowing of the speed” in his bow arm, “so that it has that feeling of running out of oxygen.”

But most of the time, “the words don’t tell you what to do,” he said. “They tell you how to be.”

On its own, musical notation is most efficient at representing pitch, duration and rhythm. Early composers relied on the instincts of performers who came from the same cultural ambit, because more elusive qualities like mood, character and gesture were hard to capture in ink. As music printing disseminated scores beyond the reach of their creators, the need for more complex performance instructions grew. The most pressing concern was tempo.

Before the invention of the metronome, there was no mechanical way to indicate speed. So composers turned to words — not to describe how fast, exactly, but how the music should feel. Terms that we now associate with metronomic values, began as cues for character. “Allegro” meant cheerful; “grave,” solemn; “andante” suggested the gentle forward motion of a walk.

“Before the metronome, composers used affect to get at tempo, not because it was precise, but because it was the best way to communicate a feeling,” said Roger Mathew Grant, a music professor at Wesleyan University and the author of a book on affect and music.

For instance, Handel’s “Water Music” has a hornpipe marked “Allegro maestoso,” indicating both the speed and the gait of the music. In the 19th century, emotional cues began to proliferate, with some composers supplementing the Italian of musical convention with words in their own language. Grüning pointed to a word Beethoven used in an accelerating passage in his Op. 132 String Quartet: “immer geschwinder,” an adjective that conveys more than the direct English translation of “ever faster.” In the score, the word appears alongside the Italian “accelerando.”

“That expression comes from old German and means not only quick, but also like energetic, brave or forceful,” Grüning said. “So it has a sense of propulsion or urgency to it. Literary figures of the time, like Goethe and Schiller, would often use it in context with haste, impulse or anxiety, so there’s a psychological aspect to it that doesn’t translate if you just write ‘accelerando.’ So Beethoven writes both.”

After Beethoven, composers began peppering their scores with expressive paratext. Mahler’s symphonies bristle with German instructions, such as “Mit Wut” (“with fury”) in the Ninth Symphony. A typical indication in Debussy is “élégant, gracieux, presque rien” — “almost nothing.”

But as language seeps into music notation, the ambiguity remains. What, exactly, does “elegant” mean? And is “almost nothing” a more precise dynamic than pianissimo?

I wonder whether Satie used performance indications like “on yellowing velvet” and “pale and priestlike” for more than just laughs. At a time when performance was an increasingly specialized activity divorced from composition and improvisation, his poetic surrealism seems to invite the player into a co-creative role that disables logic in order to make space for something else. He might be leaning into ambiguity not to obscure, but to liberate.

In contemporary music, too, scores function as blueprints not just for how music should sound, but also for how it should be approached. Often that means pushing beyond symbols and language. Terry Riley adorns his scores with colored-pencil drawings of dreamlike figures swimming, floating and levitating.

George Crumb, who died in 2022, put equal amounts of care into the visual poetry of his scores as into fashioning his otherworldly sounds. Some of his pieces are laid out in spirals, mandalas or cruciform shapes. These patterns can’t be perceived by the listener, but they coax the performer into approaching the music as ritual and inner choreography. Crumb’s imagery is enhanced with instructions like “wildly fantastic, grotesque” and “very lonely, timeless and vast.”

In an interview, the flutist Claire Chase said that the language and imagery appended to scores “are not side notes” but, rather, are essential clues.

“They shape how I breathe, how I touch the instrument, how I listen to myself and to others,” she said. “They’re not decorative. They’re directive, in a deeper way.”

Chase recalled preparing a piece by Liza Lim that included a silent interlude notated only with the instruction to give metta — a form of lovingkindness meditation — for one minute. There were no notes to play. The instruction was not to be spoken or printed. Chase said she prepared for that moment as rigorously as for any technical passage, studying, practicing and testing her ability to hold space in silence. “It’s a gesture that doesn’t leave a sound trace,” she said. “But it absolutely alters the way the next thing is heard.”

Thorvaldsdottir said that her metaphor of musicians playing a sustained note like a tightrope artist carrying a delicate flower came out of observation.

“When musicians have a long sustained tone, there can be a tendency to feel as if that note is passive and should be in the background,” she said. “But I want them to feel the weight and the fragility of what they’re carrying, a sense of care and that the note is precious and important.”

The question of how to activate a sense of care in the performer is central to music, especially in the Western classical tradition. Otherwise, it could risk becoming a culture of flawless execution. Whether the page is loaded with markings or nearly blank, the burden of meaning always falls to the player.

Philip Glass cuts an interesting figure in this debate. His scores are famously spare — no poetic metaphors, no performance instructions. Among his most popular works are the Piano Etudes, which are notated with nothing more than meter, pitches and an occasional hairpin. Yet in an interview with Ira Glass (his cousin), the composer recalled telling a pianist to play the Etudes with less metronomic precision. What he wanted was “more like Schubert,” he said. Asked why he did not give the performer more guidance in the scores, he said, “I don’t tell them what to do, because if I tell them what to do, the whole procedure becomes corrupted.”

That last word is telling. It’s not the purity of the work or even his own intentions that Glass seems concerned with, but rather the process by which an idea is handed from the composer to the performer and turned into sound. The absence of language becomes a blank surface for the musician, who is invited to enter the creative process. This trust in a performer isn’t so different from Satie’s mischief or Crumb’s mysticism.

Whether extravagant, oblique or austere, these markings don’t step outside the score — they deepen it. Expanding notation beyond musical symbols activates the full intelligence of performers at the mysterious moment when an idea is entrusted to them. In that handover, a composition requires not only skill, but also imagination, empathy and a willingness to breathe the whole of human experience to life into sound.