The harpsichord, invented around 1500, was the dominant keyboard instrument of the Baroque era. It worked by plucking a string with a small quill when a key was depressed. The system was elegant — but it had a stubborn limitation. Every note came out at exactly the same volume, regardless of how hard the player struck the key. There was no way to play softly, then loudly, then softly again.

Composers developed elaborate workarounds. They used multiple keyboards. They added stops to engage different sets of strings. They wrote for ensembles where a soloist could be heard against a quieter background. None of it solved the underlying problem. Music was, fundamentally, dynamically flat.

Bartolomeo Cristofori was an instrument maker employed by the Medici court in Florence in 1700. He spent decades on the problem. His solution was an action that struck the strings with a hammer — but, crucially, a hammer that immediately bounced back so the string could vibrate freely. The harder the player pressed, the harder the hammer hit. Volume became expressive again.

Cristofori called his invention il gravicembalo col piano e forte — the harpsichord that plays soft and loud. The name shortened to pianoforte, then piano.

Adoption was slow. The harpsichord still dominated for another 50 years. Bach played one of Cristofori's pianos in 1747 and was unimpressed. But by Mozart's generation, the piano had taken over. Beethoven wrote for it. Chopin reshaped its repertoire. Liszt made it a virtuosic spectacle.

Today there are around 50 million pianos in the world. Almost every classical concert and most popular music depends on the instrument an obscure Florentine craftsman invented to solve a problem nobody else had bothered with.