The lost plays of the Athenians

The blog 'Classic Plays' says that we need not worry that the accident of survival has left us with a body of plays which the Athenians would have regarded as mediocre.  But should we worry that some masterpieces have been lost?  Tom Stoppard suggested in his play 'Arcadia' in 1993 how we should think about that.  In a scene set in 1809 a young girl, Thomasina Coverly, and her tutor, Septimus Hodge, discuss the consequences of the mass destruction of papyri in the burning of the library at Alexandria, allegedly by Julius Caesar in 48 BC.  There is the following dialogue:

THOMASINA:           I hate Cleopatra.  Everything is turned to love with her.  I never knew a heroine that makes such noodles of our sex. It only needs a Roman general to drop anchor outside the window and away goes the empire like a christening mug into a pawn shop.  She embraced the enemy who burned the great library of Alexandria without so much as a fine for all that is overdue.  Oh, Septimus! - can you bear it?  All the lost plays of the Athenians!  Two hundred at least by Aeschylus, Sophocles, Euripides - thousands of poems - Aristotle’s own library brought to Egypt by the noodle’s ancestors!  How can we sleep for grief?

SEPTIMUS:                By counting our stock.  Seven plays from Aeschylus, seven from Sophocles, nineteen from Euripides, my lady!  You should no more grieve for the rest than for a buckle lost from your first shoe, or your lesson book which will be lost when you are old.  We shed as we pick up, like travellers who must carry everything in their arms, and what we let fall will be picked up by those behind.  The missing plays of Sophocles will turn up piece by piece, or be written again in another language.  Ancient cures for diseases will revel themselves once more.  Mathematical discoveries glimpsed and lost to view will have their time again.  You do not suppose, my lady, that if all of Archimedes had been hiding in the great library of Alexandria, we would be at a loss for a corkscrew?

Just reading that makes the hairs on the back of my neck stand up.  And ten years after Stoppard wrote those lines came this: http://news.bbc.co.uk/1/hi/entertainment/3269965.stm - not a complete long-lost play of Aeschylus but who knows what may turn up one day.