I've always been fascinated by the number of half tones in the musical scale: 12. I guess other scales have more tones but they're a little busy and strange for my taste. On a guitar fretboard, you can clearly see that the octave length is cleanly divided by 12, usable notes.
12 is a unique number. It is devisable by the first four integers. For some reason, it has obtained cultural value: 12 apostles, 12 members of a jury, 12 months in the year (Aren't there actually 13 moons?).
Looking further at the musical scale, there are 7 tones in the Do, Re, Mi scale. 7 seems to work for weekly division also. The 5 tones left over from the gleaning of the 7 useful tones, form a scale of their own, the name of which escapes me. You can sample this by doodling with the black keys of a piano, of which there are 5. There's a strong simplicity about the scale. It's harder to sound bad in it. 5 is involved as a useful building blocks of nature, from molecules to geodesic domes. We have 5 fingers. Coincedence?
