A bust created at his death, and dedicated by his son, was discovered at Smyrna, and art historians date it to around 135 CE.
Its status as a compilation of already-established knowledge and its thorough citation of earlier sources is part of what makes it valuable.
Theon quotes a poem by Alexander of Ephesus assigning specific pitches in the chromatic scale to each planet, an idea that would retain its popularity for a millennium thereafter.
Here Theon affirms the spherical shape and large size of the Earth; he also describes the occultations, transits, conjunctions, and eclipses.
However, the quality of the work led Otto Neugebauer to criticize him for not fully understanding the material he attempted to present.
In these times, Pythagoreans did not rely on irrational numbers for understanding of harmonies and the logarithm for these semitones did not match with their philosophy.
He discusses the Pythagoreans method of looking at harmonies and consonances through half-filling vases and explains these experiments on a deeper level focusing on the fact that the octaves, fifths, and fourths correspond respectively with the fractions 2/1, 3/2, and 4/3.