The Art of Poetry: To the Pisos (189)

Let a play which would be inquired after, and though seen, represented anew, be neither shorter nor longer than the fifth act. Neither let a god interfere, unless a difficulty worthy a god's unraveling should happen; nor let a fourth person be officious to speak.[*]

Let the chorus[*] sustain the part and manly[*] character of an actor: nor let them sing any thing between the acts which is not conducive to, and fitly coherent with, the main design. Let them both patronize the good,[*] and give them friendly advice, and regulate the passionate, and love to appease thou who swell [with rage]:[*] let them praise the repast of a short meal, the salutary effects of justice, laws, and peace with her open gates; let them conceal what is told to them in confidence,[*] and supplicate and implore the gods that prosperity may return to the wretched, and abandon the haughty.

The flute,[*] (not as now, begirt with brass and emulous of the trumpet, but) slender and of simple form, with few stops, was of service to accompany and assist the chorus, and with its tone was sufficient to fill the rows that were not as yet too crowded, where an audience, easily numbered, as being small and sober, chaste and modest, met together. But when the victorious Romans began to extend their territories, and an ampler wall encompassed the city, and their genius was indulged on festivals by drinking wine in the day-time without censure; a greater freedom arose both to the numbers [of poetry], and the measure [of music].[*] For what taste could an unlettered clown and one just dismissed from labors have, when in company with the polite; the base, with the man of honor? Thus the musician added[*] new movements and a luxuriance to the ancient art, and strutting backward and forward, drew a length of train over the stage; thus likewise new notes were added to the severity of the lyre, and precipitate eloquence produced an unusual language [in the theater]: and the sentiments [of the chorus, then] expert in teaching useful things and prescient of futurity, differ hardly from the oracular Delphi.[*]