Symbolism, Imagery, Allegory
The last image Ionesco leaves us with is a stage full of seemingly empty chairs. We figure this has to be symbolic of something. As we mention in "What's Up With the Title?" and in our section on the theme "Art and Culture," these chairs seem intended to remind us that in many ways we're watching a play within a play. When the Orator delivers his nonsensical message to the invisible guests, the audience is reminded of the nonsensical play they've just watched. With this in mind, it could be said that the chairs symbolize the audience itself.
Also notice that these rows of chairs are empty, at least of visible people. We wonder if this could possibly symbolize the emptiness of all our lives. This would in some ways seem to go along with the Existentialist idea that our lives are ultimately meaningless. When the sound of the invisible crowd rises hauntingly over the empty chairs at the end of the play, we are reminded of the possibility that everything we do may have no ultimate meaning.