Hold a mirror up to nature
Hamlet:
Suit the action to the word, the word to the action, with this
special observance, that you o'erstep not the modesty of nature:
for any thing so o'erdone is from the purpose of playing, whose
end, both at the first and now, was and is, to hold as 'twere the
mirror up to nature: to show virtue her feature, scorn her own
image, and the very age and body of the time his form and
pressure.
Hamlet lectures the actors who will soon perform for his stepfather [see TRIPPINGLY ON THE TONGUE]. As director, he expounds the "purpose of playing," which, from the invention of theater, has been to hold "the mirror up to nature." Here, Hamlet echoes classical authors, who insisted that drama be a form of truth, not mere entertainment. Playwrights and players should strive to present action in the most verisimilar manner, without exaggeration or distortion, without bombast or excessive sentimentality. In the theatrical mirror we see our virtues and vices reflected back to us in their true shape: that's the theater's moral function. Defensive dramatists, who had to contend with accusations of corrupting the masses, were fond of pointing out that their productions did indeed have the effect Hamlet advertises [see THE PLAY'S THE THING].