The 4th century is far more important. Early in the century is Plato
(429-347), the incomparable idealist, whose 'Timaios' is largely devoted to
music, not to speak of allusions in other dialogues. His famous pupil Aristotle
(384-322) is said to have written a musical treatise, now lost, besides
many passages in extant works—not counting the 'Problems' once ascribed
to him. Among his followers were Adrastos, from whose 'Harmonics' some
extracts have survived; and especially Aristoxenos of Tarentum (b. c. 354),
whose 'Harmonic Elements' is our earliest complete treatise, and of whose
'Rhythmic Elements' some fragments exist. He stands at the head of a
school (the Harmonici) hostile to the extreme mathematical notions of the
Pythagoreans.
In the 3d century the great name is Euclid, the Alexandrian geometer, to whom two complete treatises have been ascribed, that on the 'Partition of the Canon' probably with right, while the 'Harmonic Introduction' is now thought to be by Kleonides. The latter belongs in the 2d century, along with Eratosthenes and Hero, both Alexandrians.
From the 1st century we have Philodemos the Epicurean, whose diatribe on the uselessness of music was found at Herculaneum; and the Alexandrian grammarian Didymos (b. 63), among whose many works several on music are quoted, and to whom an account of the strife between the Canonici and the Harmonici is attributed, perhaps improperly. Here Latin writers appear for the first time, including Lucretius (95-51), treating the origin of music in his 'De rerum natura'; Cicero (106-44) and Horace (65-8), both evidently musical connoisseurs; and Vitruvius, who includes musical references in his great work 'De architectura.'
After the Christian Era, to the 1st century belongs the elder Pliny (22-79), whose 'Historia mundi' often mentions music. Greek writers include Plutarch (50-120), the author of the earliest extant historical book; Dio, among whose eighty orations are many musical remarks; and Aristides Quintilianus, who has left an important work 'On Music.'
In the 2d century the names are many and striking. Here belong Claudius Ptolemæus of Alexandria, whose 'Harmonics' is one of our chief sources; Theon of Smyrna, whose expansion of certain of Plato's ideas is partially preserved; Gaudentios, an Aristoxenian, whose 'Harmonic Manual' is extant; and Bacchios the elder, whose 'Introduction to Music' is important. Besides these appear remarks of a more or less gossipy nature from Gellius, a Roman dilettant, the satirist Lucian (125-200), and Athenaios (b. 160), an Alexandrian rhetor.
To the 3d century are assigned Aelian, whose so-called 'History' supplies some citations; Diogenes Laertios, who gives some biographical details; and Porphyry (233-305), the commentator upon Claudius Ptolemæus.
The 4th century is marked by Alypios, whose 'Musical Introduction,' preserved in part, is of the greatest value as the key to Greek musical notation.
The 5th century supplies Macrobius, whose 'Commentary' includes a fruitless discussion of 'the music of the spheres'; Proclus (412-485), with a commentary on Plato's 'Timaios'; and Martianus Capella, a Roman grammarian,
