For Mr. Hu, the small victories that Ms. Liu and others are winning represent the first stirrings of an irresistible tide of change.

“I live in Beijing, and three weeks ago there was almost no green,” he said in an interview after his release from detention. “Now it is green every day. You wouldn’t notice it if you were living it day to day, but the greenness is blooming everywhere now. It is the same with civil society, or with NGO’s. Now there is a citizens’ consciousness to participate, a willingness to defend their rights. Call it civic power.”