Meditation 11.6
6. First of all tragedies were put on the stage to remind you of what comes to pass and that it is Nature's law for things to happen like that, and that you are not to make what charmed you on the stage a heavy burden on the world's greater stage. For you see that those events are bound to have that ending and that even those endure them who have cried aloud: 'Alas! Alas! Cithaeron.' There are also valuable sayings in the dramatists; an especially famous one, for instance:
'Were the gods careless of my sons and me,
Yet there is reason here',
and again:
'Man must not vent his passion on mere things',
or:
'Life, like ripe corn, must to the sickle yield',
and the many others of the same sort.
After Tragedy was introduced the Old Comedy, which through its instructive frankness and its reminder by actual plainness of language to avoid vanity was not without profit, and this directness Diogenes also adopted with a somewhat similar object. After the Old, observe what the Middle Comedy was like and afterwards with what end the New Comedy was adopted, passing little by little into a love of technique based on imitation. It is recognized that there are profitable sayings of these authors also, but after all what was the object to which the whole aim of such poetry and drama looked?