CHINA’S HIGH-SPEED rail network is a potent symbol of that country’s headlong drive to modernize. Passengers board the sleek bullet trains and are whooshed away at more than 200 miles per hour, clutching smartphones and reading magazines about luxurious lifestyles. China’s huge middle class is brimming with ambition and rarely unplugged; the number of people who use Chinese microblogs, similar to Twitter, is estimated to have surpassed 250 million.

But strangely, the men who rule China, who have done so much to unleash this rush to wealth and modernity, are stubbornly resisting the speed and freedom of the Information Age. In an effort to arrest the digital revolution, they have created the largest Internet censorship operation in the world, hoping to control what people see, read, hear and say online.

The latest example came at the end of June. In a 4,245-word article drawing on public records, Bloomberg News described the accumulation of assets by relatives of Xi Jinping, who is expected to become China’s Communist Party leader this fall and the country’s president early next year. The article said Mr. Xi’s extended family holds investments in companies with total assets of $376 million. While no wrongdoing was ascribed to Mr. Xi, the article contrasted the family’s business interests with Mr. Xi’s own warning to politicians: “Rein in your spouses, children, relatives, friends and staff, and vow not to use power for personal gain.”

When the article was published on the Bloomberg News Web site, Chinese censors swiftly blocked the site. On microblogs, searches for English terms such as “Bloomberg,” “Xi Jinping” and “crown prince” were blocked. Mr. Xi is among the scions of China’s revolutionary fighters, a new generation known as the “crown princes” who are vying for power and influence. Another of them, Bo Xilai, was ousted this year as party chief of Chongqing in an alleged graft and murder scandal. There is increasing anger and resentment in China over powerful families enriching themselves. No wonder, then, that the censors were quick to throw the switch on the article about Mr. Xi’s family.

Censorship is born of fear. China’s leaders can’t tolerate open questioning and dissent. . But such a vast censorship machine is also a sign of weakness. It breeds popular mistrust in the leaders and is futile in a world so saturated with communications. A year ago, a high-speed train rammed into a stalled train outside Wenzhou in Zhejing Province, killing 40 people and injuring 191. Microbloggers responded with a torrent of messages — millions of them — reporting from the scene and criticizing the government’s handling of the accident. There is a lesson here for Mr. Xi. Rather than block the report about his family finances, he ought to realize that, just like the hurtling bullet trains, free and open information is critical to China’s future as a modern superpower.