Theatre is...

The director of the play I was in told us something that I thought was interesting/important to this class.  Before our last show, she said "Theatre is the only living, breathing art form."  This is getting specific--performance of any kind really falls under this umbrella.  But I think that that's true.  You can set down a painting or a poem and it's still art, whether or not you're doing anything with it.  You can compose a symphony, or write a play, and it will be there as long as the paper it is printed on is not destroyed.  But acting and playing an instrument require your breath, your body, your mind.  These are forms of art that cannot live on their own--they need someone to actively participate.

Are there other art forms that could be described as "living" or "breathing?"

Answer to Brycen's Question

Brycen asked: "If art has such a deep meaning, how can some people look at a painting and know exactly what it is trying to convey?"
My first reaction is, do they really know, or do they just think they do?  It might seem perfectly clear to someone what a painting or other work of art signifies, but they might just be projecting their own feelings and experiences onto the work.  On the other hand, they might recognize the symbols being used by the artist and actually understand the work.  Of course, the exact wording of the question changes the answer.  I'm not sure it's possible to know exactly what the artist was trying to convey unless the observer knows the artist and what he or she was thinking at the time the art was created.