Chinese President Xi Jinping in Hong Kong on July 1, 2017. (Kin Cheung/AP)

TSINGHUA UNIVERSITY prides itself on being in the top tier of China’s higher education, with 20 schools and 58 departments in science, engineering, humanities, law, medicine, history, philosophy, economics, management, education and art. But on this prestigious campus in a leafy corner of Beijing, there is little freedom to protest the lengthening shadow of President Xi Jinping’s authoritarianism and his demand for rigid loyalty to the Communist Party. Just ask professor Xu Zhangrun, who has been suspended from teaching and research because he dared question both.

We noted last summer that Mr. Xu was saying interesting things in a very open way. On July 24, he published a lengthy essay, drawing upon ancient Chinese philosophy, literature and political theory, to squarely question China’s current direction. He described Mr. Xi as a throwback to Maoism and said “an emergency brake must be applied to the personality cult” of the Chinese president, expressing fear that China is returning to totalitarianism with the elimination of term limits on the president. Translator and Sinologist Geremie R. Barmé said the “content and powerful literary style” of Mr. Xu’s piece, “as well as its tone of ‘moral outrage,’ not to mention the author’s scathing humour, will resonate deeply throughout the Chinese party-state system, as well as within Chinese society and among concerned citizens more broadly.” Mr. Barmé added that Mr. Xu’s “powerful plea is not a simple work of ‘dissent,’ as the term is generally understood in the sense of samizdat protest literature.” Rather, he said, “Xu has issued a challenge from the intellectual and cultural heart of China, to the political heart of the Communist Party.”

As Mr. Barmé predicted, the piece was widely shared, despite censorship, and Mr. Xu published more. Now, the Chinese authorities are striking back. This week, Mr. Xu said several university officials have ordered him to stop all teaching and research and that his pay would be cut drastically. He said a university “work team” would investigate the articles he wrote since July, an echo of Mao’s Cultural Revolution, when intellectuals were investigated by such teams. “I don’t know what they’ll do next,” he said in mobile phone messages, the New York Times reported. “I’ve been mentally preparing for this for a long time. At the worst, I could end up in prison.”

Over the past few years, Mr. Xi has been unflinching in his demands for fealty to Chinese political ideology, insisting that educational institutions, as well as the news media and others, show loyalty to party, China’s socialism and a doctrine called “Xi Jinping Thought.” Those who resist are punished and in many cases find themselves locked up for years at a time. What’s happened to Mr. Xu is a warning that will chill other educators. Once again, Mr. Xi stifles free thinking, that essential ingredient for any successful university — and, ultimately, any successful society.