Text: Your quote should say the 5 Great Studies- check the Timeaus & Critias of Plato Arithmetic, Geometry, Stereometry, Astronomy and Music.   Stereometics, the study of three dimensional (or n-dimensional forms) in themselves was largely ignored because it appeared to bo "obvious"  However, three dimensional forms (i.e. the 5 Platonic Solids) and their uniqueness hides the mystery.  I was led to quaterions and more in this relationship.  The idea of Stereometrics is discussed at lenght in Plato's Republic as a dialogue between Socrates and Plato.

See Also:

Source: