As nightfall does not come all at once, neither does oppression. In both instances, there is a twilight when everything remains seemingly unchanged. And it is in such twilight that we all must be most aware of change in the air — however slight — lest we become unwitting victims of the darkness.
Source, in full
Letter to Young Lawyers Section of the Washington State Bar Association (10 September 1976), The Douglas Letters : Selections from the Private Papers of Justice William O. Douglas (1987), edited by Melvin I. Urofsky and Philip E. Urofsky, p. 162.