Here's a Wall Street Journal report to send shivers down the spines of the old gray men ruling Beijing, emphasis mine.

More than one million people have moved from mainland China to live, work and study in Hong Kong since 1997, when the U.K. handed over the city’s sovereignty to Beijing. Many of them share the antipathy for the protesters expressed by state-media portrayals across the border. Some, like a group of immigrants from Fujian province in the city’s North Point neighborhood, even fought against the protesters, answering a call from Beijing. But a small cohort of mainlanders have joined the demonstrations, taking extraordinary risks to support a society that offers freedoms unavailable back home. “My understanding is that ‘one country, two systems’ is a creative set of ideals,” Ms. Chen said. “Now those ideals are threatened.” In more than a dozen interviews, these outliers said they value Hong Kong’s autonomy from Chinese control, especially when it comes to the city’s legal system and freedom of expression. They have joined marches, signed open online letters supporting Hong Kong and defended the movement in social-media battles against state-backed critics and misinformation.

In short, there's evidence that amid that sea of millions of Hongkongers protesting communism from China, some of them are mainland Chinese. Message: the mainland Chinese are getting ideas. The Chicoms of Beijing cannot wall them out from Hong Kong nor can they stop this.

And this raises the specter of what happens when they return to China, because many of these Chinese have their families there, and they will. Are these Chinese going to return back to China and spread that democracy 'virus' they passionately embraced in Hong Kong, kicking off similar protests in Chengdu, Tianjin, Harbin, Shenzhen, Wuhan and other giant cities to duplicate what the Hongkongers launched? It actually seems plausible. What's more, it will be an awakening as Chinese finally come to the realization that they deserve the same freedoms their fellow Chinese in Hong Kong have enjoyed until recently. When ten or twelve Chinese megacities start holding the kinds of protests Hong Kong is holding, Bejing's old gray rulers will have a hell of a problem on their hands. And that is their worst, their very worst, nightmare.

Such protests would signal that the Mandate of Heaven is about to fall and big changes will be in store. That would explain why China's rulers are acting so nervous about it, desperate to check cellphones of returning mainlanders and whip out the facial-recognition technology. If the Hong Kong protests spread to the mainland as a result of the regime's failure to pacify the tiny enclave, that Mandate will, ironically enough, go down into Victoria Harbour.

Let's hope it happens.

Image credit: VOA/AFP screen shot, via shareable YouTube video.