Themes
Small whole numbers
Consonance is frequency ratios of small integers, and it has been known since Pythagoras. Almost everything interesting follows from those integers refusing to line up.
The comma that will not close
Twelve fifths do not equal seven octaves. Every tuning system in history is a different decision about where to hide the difference.
The ear is not a microphone
Loudness is not amplitude, pitch is not frequency, and a note whose fundamental is missing still has one. Perception is a model, not a measurement.
The same shape, moved
A chord, a scale and a rhythm are all patterns that keep their identity when shifted. What survives the shift is what the theory is about.
What the room does
No sound reaches an ear unmodified. Reflection, absorption and resonance are part of the instrument, and always have been.
Notation hides things
Staff notation is a five-hundred-year-old compression. What it records beautifully and what it cannot record at all are both worth knowing.
Time is a circle
Rhythm drawn as a line looks arbitrary. Drawn as a cycle, the patterns that recur across continents turn out to be the same few shapes.