Hsü Kuang-ch'i 徐光啟 (T. 子先 H. 玄扈 ), Apr. 24, 1562-1633, Nov. 8, scholar and official, was a native of Shanghai. He became a hsiu-ts'ai in 1581, but failed several times in the provincial examinations. For a time he taught the children of a family at Shao-chou, Kwangtung, where in 1596 he met the missionary Lazare Cattaneo (see under Li Chih-tsao), and thus came into contact for the first time with Christianity. Later he went to Peking where in 1597 he passed the Shun-t'ien provincial examination for chü-jên with high honors. In 1600, while passing through Nanking on his way to Peking to take the metropolitan examination, he met Matteo Ricci 利瑪竇 (T. 西泰, 1352-1610). Three years later a number of scholars, including Ch'êng Chia-sui [q.v.], took part in the celebration of the seventieth birthday of Hsü 's father, Hsü Ssŭ-ch'êng 徐思誠 (T. 子望 H. 懷西, 1534-1607). In the same year (1603) Hsü Kuang-ch'i went to Nanking to visit Ricci, but the latter had gone to Peking. However, he met Jean de Rocha (see under Ch'ü Shih-ssŭ ), and was baptized by the latter under the name Paul ( 保祿 ). In 1604 he became a chin-shih, and was selected a bachelor in the Hanlin Academy. During his stay in Peking he and Li Chih-tsao [q.v.] received instruction in various subjects from Ricci, and from 1604 to 1607 Hsü worked continuously with Ricci, translating works on mathematics, hydraulics, astronomy and geography. He thus earned the distinction of being the first Chinese to translate European books into the Chinese language. One of the most influential of these translations was Euclid's Elements, published under the title 幾何原本 Chi-ho yüan pê n, (6 chüan, recorded by Hsü from dictation by Ricci. After several revisions it was published in final form in 1611. The remaining nine books of Euclid were translated into Chinese by Li Shanlan [q.v.] in collaboration with Alexander Wylie (see under Li) and were printed in 1858. During the period 1606-08 a work on trigonometry was written by Hsü, from oral dictation by Ricci, under the title 測量法義 Ts'ê-liang fa-i, 1 chüan . To compare the system of angular measurement in the ancient work, 九章 Chiu-chang (or Chiu-chang suan-shu 算術 ), with the western method, Hsü wrote a work, entitled 測量異同 Ts'ê-liang i-t'ung, 1 chüan, in which he pointed out the identity of the two methods. A work on right-angle triangles, entitled 勾股義 Kou ku i, in 1 chüan, is also attributed to Hsü . The above-mentioned four works were later included in the Hai-shan hsien-kuan ts'ung-shu (see under P'an Chên-ch'êng).
In 1606 Hsü invited his father to Peking where the latter was baptized under the name Leon ( 良 ). Hsü Kuang-ch'i's son, Hsü Chi 徐驥 (T. 龍與, 1582-1645), was also baptized under the name Jacques ( 雅各伯 ). Not long after Hsü became (1607) a corrector in the Hanlin Academy, his father died. He thereupon resigned and went home to observe the period of mourning. On his way through Nanking he invited Cattaneo to preach in Shanghai, but the latter did not come until the following year when through Hsü 's efforts Cattaneo baptized a number of Chinese converts. On the west side of his own residence Hsü built a church in which large companies of believers gathered. During this period of mourning he went twice to Macao in order to visit the churches of that colony. Upon his return to Peking in 1610 he learned that Ricci had died a few months earlier, and had been buried in a cemetery donated by the Emperor. By the end of the year Hsü was re-instated in his former post as corrector in the Hanlin Academy. About this time (December 15, 1610) an eclipse of the sun was miscalculated by the Imperial Board of Astronomy, whereas the calculations made by Pantoja (see under Li Chih-tsao) proved to be correct. It was recommended, therefore, that Hsü, with the assistance of Li Chih-tsao, Ursis (see under the former), and Pantoja, should be commissioned to translate Western calendrical material for the use of Chinese astronomers. The project, however, had not gone far when it was discontinued. In 1612 Hsü was made a  reviser in the Historiographical Board, and in the same year wrote (from Ursis' dictation) and published a work on western hydraulics, entitled 泰西水法 T'ai-hsi shui fa, 6 chüan, which was later included in the Nung-chêng chüan-shu (see below) and was copied into the Ssŭ&ucric;-k'u Manuscript Library (see under Chi Yün). In 1613 a number of instruments for the use of astronomical calculation were constructed with the help of missionaries. But owing to illness Hsü resigned in the same year and retired temporarily to Tientsin where he cultivated a farm and wrote a number of articles, such as 闢釋氏諸妄 P'i Shih-shih chu-wang (commonly known as P'i-wang ), 1 chüan, a short treatise denouncing Buddhism;諏諮偶編 Tsou-tz'ŭ; ou-pien, 1 chüan ; and a preface to the T'ung-Wên suan-chih (see under Li Chih-tsao).
In 1616 Hsü Kuang-ch'i was recalled and reinstated in his former post as reviser in the Historiographical Board. But about this time a renewed persecution of Christians was begun in consequence of a memorial which Shên Ch'üeh (see under Li Chih-tsao) submitted to the throne in the fifth moon of 1616. In this crisis a number of Christians, including Alphonse Vagnoni (see under Han Lin), were arrested at Nanking. To answer Shên's charges against the missionaries, Hsü presented a memorial, later known as 辯學疏稿 Pien-hsüeh shu-kao, in which he praised the missionaries as "disciples of the sages" ( 聖賢之徒 ). During this period of persecution most missionaries sought safety in the families of Hsü Kuang-ch'i, Li Chih-tsao, Yang T'ing-yün [q.v.] and their relatives.
Early in 1617 Hsü was advanced to assistant secretary of the Supervisorate of Imperial Instruction, but owing to illness retired three months later to his farm near Tientsin. In 1618 when Fu-shun was taken by the Manchus, Hsü was recalled to Peking to be Supervisor of In struction, and concurrently a censor. On August 7, 1619 he petitioned the Emperor to dispatch him to Korea as a special envoy to advise the Korean government in its struggle against the Manchus. Though the petition was disallowed, H s ü was ordered, on November 28 of the same year, to drill newly appointed recruits at Tungchow, east of Peking. Owing to lack of funds he asked his friends to contribute money to support the troops, and at the same time ordered from Macao four cannon of western design. These cannon did not get farther than Kuanghsin, Kiangsi, though destined for the capital. When Chu Yu-chiao [q.v.] ascended the throne (1620), it was ordered that Hsü must reduce his troops to 4, 600 men. In the following year he once more retired to Tientsin on grounds of ill health. In the meantime (1621) Shên-yang and Liao-yang fell to the Manchus (see under Hsiung T'ing-pi) and Hsü was again recalled to the capital, whereupon he once more (July 1, 1621) petitioned the emperor to send him on the above mentioned mission to Korea. But as the suggestion was strongly opposed by Ts'ui Ching-jung 崔景榮 (T. 自強, chin-shih of 1583, d. 1631), then president of the Board of War, the petition was once more denied. Hsü resigned and later returned to Shanghai where he wrote, from dictation by Francis Sambiasi 畢方濟 (T. 今梁, 1582-1649), a treatise on the soul, under the title 靈言蠡勺 Ling-yen li-shuo, 2 chüan, printed in 1624. In 1622 Shên Ch'ü eh was made Grand Secretary, the persecution of Christians was renewed, and missionaries were forced to go into hiding. In 1623 Hsü was offered the post of vice-president of the Board of Ceremonies, but declined, preferring still to remain in retirement.
Early in 1628, after the accession of Chu Yuchien [q.v.], Hsü was recalled and made a diarist. In the following year he was promoted to senior vice-president of the Board of Ceremonies which later made public the results of competitive tests on the prediction of a solar eclipse that took place on June 21, 1629. Calculations were made by adherents of three schools of astronomy: the Chinese or Ta-t'ung 大統, the Mohammedan, and the Western. The predictions submitted by the first two schools were found to be erroneous whereas those submitted by Hsü were correct. A new demand arose for the revision of the calendar and Hsü, on recommendation of the Board of Ceremonies, was appointed to take charge of a newly-established Calendrical Bureau ( 曆局 ), located at Shou-shan 首善 Academy, east of the Catholic church inside the gate Hsüan-wu mên 宣武門, Peking-with Li Chih-tsao, Longobardi (see under Chu Yu-lang) and Terrenz (see under Li Chih-tsao) as assistants. Toward the close of the year (7629) Tsunhua, Hopei, fell to the Manchus, and Hsü was ordered to manufacture firearms in order to provide against a possible attack on the capital. Terrenz having died (May 13, 1630) and he himself being occupied with the manufacture of arms, Hsü recommended Johannes Adam Schall von Bell (see under Yang Kuang-hsien), and Jacques Rho (see under Han Lin) to assist in the calendrical work. In July 1630 Hsü was made president of the Board of Ceremonies. On December 4 Li Chih-tsao  died and Hsü was the only one of "The Three Pillars of the Christian Religion in China" ( 聖教三桂 ) remaining, the other two being Li and Yang T'ing-yün.
Meanwhile Hsü recommended that Longobardi and Sambiasi be commissioned by imperial decree to proceed to Macao to purchase ten cannon from Portuguese merchants and to hire a few soldiers to operate them. The cannon were purchased and the return company was led by Gonzales Texeira-Correa 石公沙的西勞 (d. 1632), a citizen of Macao, with Jean Rodriguez 陸若漢 (1559-1633) as interpreter. The cannon arrived on time to defend the city of Chochou (Hopei) against the Manchus. Later four hundred more soldiers were enlisted from Macao. When they set off overland for the capital, five missionaries, Tranquille Grassetti 謝貴祿 (T. 天爵 1588-1644), Pierre Canevari 聶伯多 (T. 石宗 1594-1675), Benoit de Mattos 林本篤 (T. 存元 1600-1652), Michel Trigault 金彌格 (T. 端表 1602-1667), and Étienne Faber, or Le Fiè vre, 方德望 (T. 玉清, 1598-1659), accompanied them in the hope of being able to preach in the interior of China. Late in 1630 the Manchus retired to Mukden and China enjoyed a temporary peace.
In 1632 Hsü was made Grand Secretary of the Tung-ko 東閣 and a year later, of the WênYü an ko 文淵閣 . Taken ill on September 11, 1633, he memorialized the throne (October 31) to reward the missionaries for their assistance to the Calendrical Bureau, and recommended Li T'ien-ching [q.v.] to succeed him in the task of revising the Chinese calendar. After two months of illness he died. Owing to the unrest in his native place his remains were not interred in the cemetery at Zikawei 徐家匯 (Hsü Family Village), in the suburbs of Shanghai, until 1644. He was posthumously awarded the honorary title of Junior Guardian (changed in 1643 to Grand Guardian) of the Heir Apparent and was canonized as Wên-ting 文定.
In 1643 Hsü Kuang-ch'i's third grandson, HsüÊr-tou 徐爾斗 (1609-1643, baptized under the name Matteo 瑪竇 ), presented to the throne a work on agriculture by Hsü Kuang-ch'i, entitled 農政全書 Nung-chêng ch'üan-shu, 60 chüan, compiled by Hsü during the years 1625-28, and later copied into the Ssŭ&ucric;-k'u Manuscript Library. The editing of this work was entrusted in 1635 to Ch'ên Tzŭ-lung [q.v.] by Hsü's second grandson, HsüÊr-chüeh 徐爾爵 (1605-1683, baptized under the name Ignace 依納爵 ), but probably was not completed until 1639. The Nung-chêng ch'üan-shu is an important compendium on agriculture, and later served as the basis of a similar work, entitled Shou-shih t'ung k'ao (see under Ch'ên Tzŭ-lung), which was compiled by an imperial order of 1737, and was completed in 1742. Ch'ên Tzŭ-lung, believing the Nung-chêng ch'üan-shu to be too long, later contracted it to 46 chüan . This edition is given notice in the Ssŭ&ucric;-k'u Catalogue (see under Chi Yün).
During his four years on the Calendrical Bureau Hsü Kuang-ch'i on three occasions (twice in 1631 and once in 1632) presented to the throne translations on astronomical subjects, comprising 72 chüan, and one table of the fixed stars ( 恆星 ). These works were all later included in the Ch'ung-chên li-shu (see under Li T'ien-ching). Hsü's collected writings were first brought together in 1663 by his fourth grandson, HsüÊr-mo 徐爾默 ( 容庵, 1610-1669, baptized under the name Thomas 多默 ), and were printed in 1896 by Father Li Ti 李杕 ( 問漁 ) under the title 徐文定公集 Hsü Wên-ting kung chi . This collection was republished in 1909 with supplementary material by Hsü Yün-hsi 徐允希 (Father Simon Hsü), a descendant of Hsü Kuang-ch'i in the eleventh generation, under the title Tsêng-ting (增訂 ) Hsü Wên-ting kung chi . It was again reprinted in 1933, with further additions, by Hsü Tsung-ts ê徐宗澤 (Father Joseph Hsü), a descendant of Hsü Kuang-ch'i in the twelfth generation. Owing to the literary inquisition of the Ch'ing period and the raids by Chêng Ch'êng-kung [q.v.] on the Shanghai coast, several decades after Hsü 's death, many of his works were either destroyed or lost. A collection of his memorials and correspondence, mostly on national defense, under the title 徐氏庖言 Hsü shih pao-yen, 5 chüan, which was banned in the Ch'ien-lung reign-period, was reprinted in 1933 from an edition preserved in the Bibliotheque Nationale, Paris. A collection of Hsü Kuangch'i's letters, entitled 徐文定公墨蹟 Hsü Wên-ting kung mo-chi, "Ink Remains of Hsü Kuang-ch'i, " was first printed in 1903 in facsimile and was reprinted in 1933.
One of Hsü's granddaughters, Candide Hsü徐甘弟 (1607-1680), who married Hsü Yüan-tu 許遠度 of Hua-ting, Kiangsu, was a zealous Christian who is reported to have established 135 chapels in and about Shanghai. Her son, Hsü Tsuan-tsêng 許纘曾 (T. 孝修, 孝達 H. 鶴沙, 悟西, a chin-shih of 1649, who was baptized under the name Basil 巴西 ), was a poet who rose to provincial judge of Yunnan. The  eldest grandson of Hsü Kuang-ch'i, named HsüÊr-chüeh 徐爾覺 (1603-1680), baptized under the name Melchior 滿覺, was also a devout Christian.
Shanghai hsien-chih (1871) 15/27a, 19/29a;學風月刊 Hsüeh fêng yüeh-kan, vol. 4, nos. 5 and 6, biography by Hsü Ching-hsien;人文月刊 Jên-Wên yüeh-kan, vol. 4, no. 7 (1933) on the tercentenary celebration;新月 Hsin-yüeh, vol. 1, no. 8, on his writings; Tung fang tsa-chih (Chinese Miscellany), vol. 30, no. 24, on his contribution to education; Revue Catholique (Shêng-chiao tsa-chih ), vol. 22, no. 11 (Nov. 1933), special number devoted to Hsü; Tsêng-ting Hsü Wên-ting kung chi (nien-p'u); Juan Yüan [q.v.], Ch'ou-jên chüan (1935), p. 390-407; Li Yên, 中算史論叢, Chung suan-shih lun-ts'ung, pp. 152-66; Annual Report of the Librarian of Congress (1934), pp. 149-50; Pfister, Notices, passim.]
J. C. YANG>