Theater is a verb before it is a noun, an act before it is a place.
Theater is like a faithful dog: it remains waiting for us, silent and hopeful.
Life is a theatre set in which there are but few practicable entrances.
All the world's a stage, and all the men and women merely players.
Theater is life. Cinema is art. Television is furniture.

The theater is a spiritual and social X-ray of its time.

Acting is behaving truthfully under imaginary circumstances.
Acting is the ability to live truthfully under imaginary circumstances.