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The reason we start the scale with C instead of A has to do with the history of music theory.
In the early medieval modal system, A was simply the lowest note in the two-octave range they used. The main mode back then was based on D, so A was just the bottom note and didn’t have any special significance.
However, during the Renaissance, harmony(화성) started to develop, and they began using C as the basis for the Ionian mode(이오니안 선법). The Ionian mode had a special feature — when you build chords in thirds on C, it naturally resolves the dissonance of the tritone (an unstable interval - interval:음정). Before this, the tritone was considered a problem and had to be adjusted using accidentals like Bb and F#.
Since C could handle the tritone without needing adjustments, it became the preferred starting point for scales. Even so, there was no attempt to rename all the notes to make A the Ionian root (이오니안 근음) — people were already used to the note names, and the names themselves didn’t have deep meanings.
In short, we use C as the starting point because of how harmony developed in Western music, not because there was a deliberate plan to make C the first note.
I started learning a new piano piece, and while playing it, I got really curious about why the scale starts on C. I also never noticed that the keyboard starts with A and ends with A. 🤯
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