What is/are the theme/themes in the play Rhinoceros?

In my mind, the most dominant theme in the play is how
individuals will be able to withstand the force of a conformist social setting.  The
fact that everyone in the village starts to become these rhinos and Berenger is the only
one who has not become a rhino.  The manner in which he deals with being the "last
human" is part of the thematic development of the work.  Berenger engages in self doubt
and a sense of agony as to why he is so different and unique.  He tries to blend in with
this conformist vision in order to avoid the pain present in being distinct.  Yet, he
resolutely affirms his own sense of identity as being against the majority at the end of
the narrative.  I think that this is probably the strongest theme to emerge because it
highlights the challenges of the individual against the social order and how there has
to be strong enough steps to safeguard against this
encroachment.