What is the theme to this poem?
When the Nazis came for the communists,
I remained silent;
I was not a communist.
When they locked up the social democrats,
I remained silent;
I was not a social democrat.
When they came for the trade unionists,
I did not speak out;
I was not a trade unionist.
When they came for the Jews,
I did not speak out;
I was not a Jew.
When they came for me,
there was no one left to speak out.