The whole history of the progress of human liberty shows that all concessions yet made to her august claims, have been born of earnest struggle. The conflict has been exciting, agitating, all-absorbing, and for the time being, putting all other tumults to silence. It must do this or it does nothing. If there is no struggle, there is no progress. Those who profess to favor freedom, and yet depreciate agitation, are men who want crops without plowing up the ground. They want rain without thunder and lightning. They want the ocean without the awful roar of its many waters. This struggle may be a moral one; or it may be a physical one; or it may be both moral and physical; but it must be a struggle. Power concedes nothing without a demand. It never did and it never will.

Frederick Douglass (1817-1895) American abolitionist, orator, writer
Speech on West India Emancipation (4 Aug 1857)

Also cited (in part) as a letter to a colleague in 1849. More background here.