It evolves progressively, always with small steps like excluding people, creating offices that serve discrimination. When no one does anything about those changes that sends a sign, too—a sign that they can go farther.
I’ll give you an example: Goebbels. After the Évian Conference in 1938, when the community of nations gathered in Switzerland to talk about taking in Jewish refugees from Germany and no one wanted to take them in, Goebbels wrote in his diary, ‘They would like to do what we are doing but they don’t have the courage.’ He took the message that if, at the first step, no one would stop him, then he could keep going.”
From the book, Willful Blindness by Margaret Heffernan