Lincoln- Douglass Debate and The Holocaust

When reading the beginning of the excerpts from Douglass in the debate, a line really struck a cord with me:

"... where will it stop? If one man says it does not mean a negro, why may not another man say it does not mean another man?"

This line almost instantly brought me back to a poem by Martin Niemoller written during the Holocaust. It is currently in the US Holocaust Memorial Museum and states:

"First they came for the Socialists, and I did not speak out--
Because I was not a Socialist.
Then they came for the Trade Unionists, and I did not speak out--
Because I was not a Trade Unionist.
Then they came for the Jews, and I did not speak out--
Because I was not a Jew.Then they came for me--and there was no one left to speak for me."

I find it incredibly intriguing how two issues in different eras of history can be responded to with similar philosophical arguments. It's disappointing but, also refreshing to see how human nature doesn't seem to change much.