Rhythm is the oldest instrument. Before language, before writing — the beat.
Zhang Guolao's fish drum keeps time for the court. This page is the drum. Scroll to conduct the tempo, move to make light, strike to sound it. The rhythm you set is the rhythm it keeps.
Scroll — conduct. Down quickens, up slows. Forty to one hundred eighty beats per minute.
Move — the cursor trails warm light, flaring on every beat.
Click, tap — strike the drum. A ring, a low tone.
The counter shows how long your rhythm has held. Endurance is the aspect — keeping the beat is the whole instrument.
Vanilla JS, one canvas, no libraries, no tracking. Sound is synthesized in your browser — nothing recorded, nothing leaves. Without JavaScript the essay still renders; the drum just sleeps.