What was a main theme in The Masque of the Red Death?

The main theme of this amazing short story by Poe is
Death.  He comes in quietly, like a thief, disguised appropriately for this masquerade
ball.  One by one, the guests drop dead and the rest retreat to other rooms.  The
purpose of the party was to keep all the wealthy friends far away from the plague that
is sweeping through the city outside.  Prospero, like his wealthy friends, thinks that
because he is wealthy and "above" the poor who are dying ouside his walls, that he is
above dying.  The truth is, no one can escape Death, no matter how rich, how beautiful,
how entitled one is. 

Another theme is time.  Throughout
the story, the clock keeps ticking loudly, and Prospero and other guests keep noticing
the time.  It is almost as though they expect an expiration date on the contagion. 
There is, however, an expiration date on the living. Everyone dies eventually.  It is
interesting to note, that the different rooms in Prospero's house correspond with the
different stages in one's life.  Take a look at the colors of each room...all the way to
the last one, which is black, signifying Death itself.