Harmonic and arithmetic division of the octave

Gioseffo Zarlino

Fourths and fifths defining the diatonic scale

Johannes Cotto

Enneagram - magic square

Athanasius Kircher

Music of the spheres

Franchino Gaffurio

Authentic and plagal modes

Johannes Cotto

Conjunctae (hexachords)

Domingo Marcos Durán

Trinity shield

Guilelmus Peraldus

Consonance Circle

René Descartes

Ut queant laxis

Beats

Thomas Young