Comment by euroderf

If tasked with this, I would start with an image of a piano keyboard and ask: Why the hell does it look so weird ? Black and white keys in some infernally strange layout ? WHY ?

Which takes you very quickly to equal temperament and perfect fourths and perfect fifths. This tells us where the notes C and F and G are located on the chromatic scale, but then the rest are pretty arbitrary eh. Semitones from C to C go 2-2-1-2-2-2-1, but there is nothing heavenly ordained by this particular arrangement. E-to-F and B-to-C are a collective choice.

If I had been presented with this kind of explanation fifty years ago, I might have been less skeptical of the entire enterprise.