First they ignore you, then they say you're mad, then dangerous, then there's a pause and then you can't find anyone who disagrees with you.

The Columbia Dictionary of Quotations, Robert Andrews, Columbia University Press, 1993, ISBN 0231071949, 9780231071949. A similar quotation is almost invariably attributed to Gandhi, but more likely derives from a 1914 US trade union address

"And, my friends, in this story you have a history of this entire movement. First they ignore you. Then they ridicule you. And then they attack you and want to burn you. And then they build monuments to you. And that, is what is going to happen to the Amalgamated Clothing Workers of America." General Executive Board Report and Proceedings [of The] Biennial Convention, Amalgamated Clothing Workers of America, 1914. Google Books