Ying-shih Yu, a renowned scholar of Chinese traditional thought who used his mastery of classical texts to trace China’s evolution across thousands of years, died on Aug. 1 at his home in Princeton, N.J. He was 91.

His family confirmed the death in a statement.

Professor Yu’s encyclopedic knowledge of Chinese thought, literature and history was grounded in a traditional education in rural China.

His early life was shaped by war, revolution and repeated dislocation. In 1937, as Japanese forces invaded China, he was sent to live with relatives in the lush, isolated countryside of streams and mountains in Anhui Province, in eastern China.

There his teachers introduced him to the rigors of reading and writing classical Chinese, far removed from the Western-inspired modern curriculum that had gained hold in cities. That instruction and his immersion in village life, he said, set him apart from many of his contemporaries.

“Through living all those years in the countryside, I unconsciously gained an intimate understanding of traditional Chinese society,” Professor Yu wrote in his memoirs, published in 2018.

In a career that took him to Hong Kong and Taiwan, as well as a succession of Ivy League universities, Professor Yu often returned to the theme that China’s long traditions could be a wellspring, not an enemy, of enlightenment, individual dignity and democracy.

When he began his studies in the 1940s, “whatever appeared to be uniquely Chinese was interpreted as a deviation from the universal norm of progress of civilization,” Professor Yu said in a speech in 2006 when he received the John W. Kluge Prize for Achievement in the Study of Humanity at the Library of Congress.“If history is any guide, then there seems to be a great deal of overlapping consensus in basic values between Chinese culture and Western culture.”

Professor Yu’s prominence in the Chinese-speaking world crossed geopolitical barriers and extended beyond academia. His death prompted widespread tributes in Hong Kong, in Taiwan and in mainland China, where his books were widely read even though his liberal values were anathema to the ruling Communist Party. President Tsai Ing-wen of Taiwan eulogized him as a “master of historical studies” and a guardian of democratic ideals.

“Professor Yu was held by many educated Chinese on the mainland as a spiritual pillar,” said Josephine Chiu-Duke, a professor of Chinese intellectual history at the University of British Columbia, who co-edited a two-volume selection of his papers published in 2016. “There will never be a second Yu Ying-shih in our time or in the future.”

Professor Yu was born in Tianjin, a port city in northern China, and gave his birth date as Jan. 22, 1930, although the date may have changed after China converted from the traditional calendar, Professor Chiu-Duke said.

His mother, Chang Yun-ching, died while giving birth to him, and his early years were shaped by the shifting jobs of his father, Yu Hsieh-chung, a history professor who had studied in the United States.

Professor Yu began his university studies in Shenyang, in northeast China, but fled amid the civil war. He later continued his education at Yenching University in Beijing, just as Mao Zedong was establishing the city as the capital of the new People’s Republic in 1949.

In 1950 Professor Yu visited his father in Hong Kong, then a British colony that was filling with refugees fleeing mainland China. When his train back to Beijing broke down, he abruptly decided to return to Hong Kong and continue his studies there.

“This was a crucial moment that determined the fate of my life,” he wrote in his memoirs, “and I will never forget it.”

Even in Hong Kong, his education remained traditional. He studied at the New Asia Academy under Ch’ien Mu, a Chinese historian devoted to traditional learning. Professor Yu devoted himself to classical Chinese scholarship, while also visiting libraries to read English-language books on history and social thought.

He went to Harvard University as a visiting scholar in 1955 and extended his stay to become a graduate student, completing his Ph.D. dissertation there in 1962. A demanding but generous teacher, he held posts at the University of Michigan, Harvard, Yale and the Chinese University of Hong Kong. In 1987 he joined the faculty of Princeton University, where he became the Gordon Wu ’58 professor of Chinese studies.

“He wrote about the full range of Chinese history,” Willard Peterson, an emeritus professor of Chinese studies at Princeton, said by email. “When we were in the formal process of voting to hire him, our cohort of China specialists together realized that Professor Yu had at least one major publication in each of our special fields.”

Professor Yu’s wife, Monica Shu-ping Chen Yu, a teacher who was also well versed in classical Chinese, was his “intellectual companion whose spirit of inquiry complemented his,” Professor Peterson said.

Joanna Waley-Cohen, the provost of New York University Shanghai, recalled in an email that once, when she was a graduate student at Yale, she and Mrs. Yu were struggling to add punctuation to a difficult passage of classical Chinese.

“She called that night and said: ‘Ying-shih says there are five different ways to punctuate this text. Any of them could be correct,’” Professor Waley-Cohen said.

Professor Yu’s essays were crowded with references to ancient Chinese thinkers as well as modern inspirations. His books included a two-volume Chinese-language study of Zhu Xi, a notoriously esoteric Confucian thinker, as well as “Chinese Intellectuals and Chinese Culture” (2003) and “The Religious Ethic and Mercantile Spirit in Early Modern China” (2021).

He believed that Chinese tradition was more varied and tolerant than critics, and some admirers, thought it to be, and that in modern times it could be a vessel for enlightened values and democratic progress. And he maintained that intellectuals, as custodians of those ideas, had a responsibility to advance those ideals.

After the Chinese government’s crackdown on the Tiananmen Square protests in 1989, Princeton began an initiative to take in exiled Chinese intellectuals. Professor Yu was a strong supporter who spoke to them about the importance of their cause.

“He was a major scholar, so his words carried more weight when he spoke out,” Su Xiaokang, a Chinese journalist and documentary filmmaker who was among the exiles at Princeton, said in an interview. “Nobody doubted his scholarship, so when he spoke out, the Chinese Communist Party could do nothing and didn’t dare criticize him.”

After retiring from Princeton in 2001, Professor Yu continued lecturing, writing and giving interviews to voice his support for democracy in Taiwan. He also lamented the recent draconian crackdown in Hong Kong. He visited mainland China as part of a delegation in 1978, but never felt inclined to return.

His survivors include his wife and two daughters, Judy and Sylvia Yu.

The Library of Congress catalog lists Professor Yu as the author of 102 books in English and Chinese, including editions published in China, Taiwan and Hong Kong.

“The kind of humanistic scholarship he personified will always garner enormous respect, perhaps especially in certain Chinese circles, but it is increasingly rare these days and sometimes dismissed as not ‘useful’,” Professor Waley-Cohen said. “He would probably ask, Who are we to predetermine what ‘useful’ means?”

Liu Yi contributed research.