When Bernie Sanders stepped to the stage on Wednesday to announce the launching of “Our Revolution,” a political organization dedicated to keeping the momentum of his presidential campaign going by supporting candidates at all levels of government, he inadvertently admitted that it wouldn’t do much good. “Real change never ever takes place from the top on down. It’s not some guy signing a bill,” Sanders said at the live-streamed launch event. “It always takes place from the bottom up when millions of people come together and demand fundamental change in the country.”

Sanders surely knows that a revolution of the kind he deems necessary isn’t likely to unfold through independent-expenditure TV ads on behalf of down-ballot candidates. In fact, that’s why most of the young organizing staff at Our Revolution quit when they saw Sanders campaign manager Jeff Weaver sliding in as president of the organization, vowing to solicit funds from wealthy contributors. “We’re organizers who believed in Bernie’s call for a political revolution,” former organizing director Claire Sandberg told NBC News. “So we weren’t interested in working for an organization that’s going to raise money from billionaires to spend it all on TV.”

The truth is that what boosted the Sanders campaign from irrelevance to prominence did come from the bottom up—not just from $27 donations, but from millions of moments of personal expression, using tools as old as leaflets and as new as Facebook. A cultural and political transformation brought Sanders, and more precisely his message, to the forefront. And the people who did it don’t need to be told how to continue the mission.

We’re in an era of leaderless political engagement at the street level, where exercising power and expressing outrage frequently mirror one another. People are demanding change not just through the ballot, but through pooling their voices for collective action. And a new book offers the first up-close profile of those who decided to stop waiting for others to fulfill their dreams of a better country—the real revolutionaries of our age.

Sarah Jaffe chronicles the burgeoning power of political protest, from Occupy Wall Street to Black Lives Matter to the Fight for $15, in Necessary Trouble. Jaffe conducts journalism in the book, actually going into communities and talking to people fighting austerity, foreclosures, corporate greed, and bigotry. In doing so, she uncovers a movement that was thriving under our noses, outside of the political arena, and often beyond the eyes of the media, long before Sanders came along. It was so much under the radar, in fact, that Jaffe had trouble finding a publisher at first. “We had the worst time selling this book in the summer of 2014,” Jaffe told me in a phone interview last week. “People were like, shrug. Then Ferguson happened.”