The theories set forth by
Pythagoras are complex to those
uninitiated into mathematical and
musical analysis, but certain concepts
are important to set forth here.
Nicomachus of Gerasa, a theorist in
the first or second century CE, was an
authority on Pythagoras and called himself a
Pythagorean. In his Manual of Harmonics, he
models his explanations of intervals, numbers,
and the music of the spheres on Pythagoras’s
teachings as passed down through the years,
and it is a good source from which to explain
some basic concepts.