Arithmetic,  Geometry,  Music, and  Astronomy.
The Quadrivium (which pertains to Matter & Quantity)- the advanced four.
 ARITHMETIC —
Number in itself, which is a pure abstraction; that is, outside of space and time.
 GEOMETRY —
Number in space.
 MUSIC OR HARMONIC THEORY —
Number in time.
 ASTRONOMY —
Number in space and time.
The Quadrivium with Gene Odening, Gnostic Media Podcast episode #050 (start here)
Quadrivium – Number, Geometry, Music, & Cosmology with John Martineau, Gnostic Media Podcast episode #103 (intermediate)
The Golden Ratio with Dr. Scott Oslen, Gnostic Meida podcast episode #108 (advanced)
The Elements of Music with Dr. Jason Martineau, Gnostic Media podcast episode #109 (advanced)