Zhong Wen: In fact, the idea that “Europeans became China’s disciples” is only superficial. What really happened? Even the so-called “scientific crystallization of the Chinese nation’s wisdom and spiritual heritage”—the current “lunar calendar”—is essentially a product reverse-engineered over 400 years ago by European Jesuit missionaries together with China’s first generation of Catholics. During its implementation, Jesuits repeatedly had to “challenge” Chinese literati—who claimed to represent “a thousand-year cultural tradition”—in head-to-head competitions. Later revisions of the calendar also relied on astronomical almanacs bought at street stalls in Paris by Portuguese priests, as well as nautical ephemerides begged from the British.

China’s present lunar calendar descends from the Qing dynasty’s Xiyang Xinfa Lishu (“Western New-Method Calendar”), which itself evolved from the late-Ming Shixian Calendar. Before Shixian, the Ming dynasty used the Datong Calendar—which was essentially the Yuan dynasty astronomer Guo Shoujing’s Shoushi Calendar under a new name. By the late Ming, however, this system had become inaccurate in relation to actual weather and astronomy, especially in predicting solar and lunar eclipses.

According to The History of Ming, in 1629 the Ming central government appointed Minister of Rites Xu Guangqi and Nanjing Taipu Temple Vice Minister Li Zhizao to lead a “Western-method reform of the calendar.” But the real work of translating and calculating was performed entirely by “Westerners Long Huamin and Deng Yuhan” and “Westerners Tang Ruowang and Luo Yagu.” All of these “men from countries beyond the great ocean” were Jesuit missionaries from Italy and the German states: Long Huamin (Johann Schreck/Terrentius) was Sicilian; Deng Yuhan and Tang Ruowang (Johann Adam Schall von Bell) were German; Luo Yagu (Giacomo Rho) was Milanese. And the leading Chinese officials—Xu Guangqi and Li Zhizao—were also China’s first Catholics, who had given up gambling and concubines. Their theoretical model was the “Tychonic system”: a hybrid between Copernicus’ heliocentrism and Ptolemy’s geocentrism—Earth at the center, the Sun and Moon orbiting Earth, but the five planets orbiting the Sun.

After the Ming–Qing transition, the Shixian Calendar was edited into 103 volumes. Emperor Shunzhi renamed it Xiyang Xinfa Lishu (“Western New-Method Calendar”) and promulgated it in 1645. From Kangxi Year 8 (1669) until the fall of the Qing, China essentially continued using Tang Ruowang’s reformed calendar—which survives today as the so-called “lunar calendar.”

Bo Ya: Isn’t that name a kind of “bait-and-switch”?

Zhong Wen: Even today’s “24 Solar Terms” of the lunar calendar come from the Jesuits’ “fixed-qi method”—sharing only the name with the “traditional 24 solar terms,” while the method and dates are entirely different.

In traditional Chinese calendars before Shixian, a “solar term” was defined by dividing the time between one Winter Solstice and the next into twelve equal parts (“zhongqi”). Each pair of adjacent zhongqi was further split into equal halves (“jieqi”). This “equal-interval method” meant every term occurred at evenly spaced dates.

But since the Jesuit reform (and still today), China’s “24 Solar Terms” are defined by the Sun’s position on the ecliptic: starting from the Spring Equinox at 0°, each 15° segment is a solar term. These intervals are not equal in time—the “fixed-qi method.”

Thus the modern “Chinese lunar calendar” shares only the names of the old system’s solar terms; their methods and dates are completely different.

Bo Ya: Isn’t that basically “using the West for China”—a total knockoff?

Zhong Wen: In 1644, the Jesuit Tang Ruowang challenged the Astronomical Bureau in a public contest predicting a solar eclipse. Only after his complete victory did the “lunar calendar” have its chance to be adopted.

The Shixian calendar faced fierce resistance. When Tang Ruowang predicted a solar eclipse during the first year of Shunzhi, officials demanded that Bureau astronomers and Tang compete. On the day of the eclipse, the results were clear: the official Datong Calendar missed by half, the Islamic calendar missed by an hour, but Tang’s predictions were “accurate to the fraction of a minute.” The Qing court declared, “The Ming refused the new method for twenty years. Our Great Qing has used it for only a few days, and already a single test aligns like matching halves of a military tally—truly miraculous!”

But Chinese literati, unable to defeat the missionaries scientifically, attacked them through political persecution—accusing them of treason, cursing the dynasty, and plotting rebellion—leading to the temporary abolition of the new calendar.

Bo Ya: That sounds exactly like the Communist Party’s habit of “putting on hats, swinging clubs, grabbing handles”—the inevitable outcome of “the unqualified leading the qualified.”

Zhong Wen: In the turbulent adoption of the “lunar calendar,” one can indeed observe some uniquely Chinese “national wisdom.” In 1664–65, officials threatened by Jesuit expertise used political accusations to make the emperor abandon the new calendar. A student, Yang Guangxian, accused Tang Ruowang of “stealing the Mandate of Heaven for the West” by writing “according to the Western new method” in the calendar. Tang was blamed for “spying on state secrets,” “colluding with internal and external forces,” and for the church’s “hundreds of thousands of converts.” The result: Tang was spared execution but soon died; five supporting Chinese officials (all Catholics) were executed; and the Qing abolished the Jesuit calendar and reinstated the old Datong Calendar.

But the Jesuits fought back. In 1668 they again competed with the Astronomical Bureau—and again won on all counts. Finally, in 1669, the Qing restored the Jesuit calendar, appointed Nan Huairen (Ferdinand Verbiest) as Deputy Director of the Astronomical Bureau, and posthumously vindicated Tang Ruowang. The calendar the Jesuits produced is essentially the one still used as today’s “lunar calendar.”

Bo Ya: The Portuguese priests who replaced the first Jesuits in China managed to keep revising the calendar using French astronomical ephemerides and British nautical almanacs. Even these untrained Portuguese missionaries could still fool Qing officials easily: “The Chinese were unable to detect their errors.”

When the 1793 British Macartney mission arrived in China, the Portuguese bishop Tomas Pereira secretly asked them for help. “The bishop admitted to the British that he and his colleagues could not predict solar or lunar eclipses, nor determine lunar phases or sunrise and sunset times—though the Qing court believed them experts.” Earlier they had managed because they could still buy French ephemerides, adjusting them using the longitude difference between Paris and Beijing.

But the French Revolution cut off this supply. Their fraud was about to be exposed. Sympathizing with the desperate “scholar,” the British gave him a set of Greenwich-based nautical almanacs valid until 1800. “Thus this bishop-astronomer—who knew nothing of astronomy—was able to enjoy seven more peaceful years.”

This was the inevitable consequence of the Qing empire’s isolation and stagnation.