First [the Nazis] came for the Communists, but I was not a Communist—so I said nothing.
Then they came for the Social Democrats, but I was not a Social Democrat—so I did nothing.
Then came the trade unionists, but I was not a trade unionist.
And then they came for the Jews, but I was not a Jew—but I did little.
Then when they came for me, there was no one who could stand up for me.”
Peter Novick, The Holocaust in American Life 221 (1999).
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This is why we protect the so-regarded "lunatic fringe" when their speakers rant and rave unpleasant things we don't want to hear.
We protect them to protect us, for in life, the worm turns, and tomorrow we'll need the protection.
To protect the center, we must protect the fringe.
Otherwise, where will you draw the line.
Much of First Amendment law regarding expression, association, petition, religion, conscience, etc., seems devoted to protecting and expanding on this principle. The litigation often takes the form of a reprehensible appearing speaker or actor expressing a view that seems outrageous.
Of course, that's how the Abolitionists who opposed slavery were regarded, weren't they.
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Another version:
First they came for the Communists, and I didn’t speak up because I wasn’t a Communist.
Then they came for the Jews and I didn’t speak up, because I wasn’t a Jew.
Then they came for the Catholics, and I didn’t speak up, because I was a Protestant.
Then they came for me, and by that time there was no one left to speak up for me.