Ch'ên Mêng-lei 陳夢雷 (T. 則震 H. 省齋, 天一道人), b. 1651, scholar, was a native of Hou-kuan (Foochow). In 1670, at twenty sui, be became a chin-shih and was selected a bachelor of the Hanlin Academy. Li Kuang-ti [q.v.], also a native of Fukien, entered the Academy in the same year and the two became intimate friends. They were made compilers in 1672, and soon afterward both asked for leave. Ch'ên, who left Peking a few months later than Li, arrived at Foochow early in 1674. The San-fan Rebellion had just broken out (see under Wu San-kuei) and Kêng Ching-chung [q.v.] staged a revolt in Fukien, forcing many local men of note to join him. Li Kuang-ti went to Foochow, but after a few days he left for his home in An-hsi and therefore was not drafted into Kêng's service. Ch'ên Mêng-lei, having his residence in Foochow, Kêng's capital, was unable to depart and so was compelled to accept a post with the rebels. Ch'ên claimed later that he feigned illness and did not serve in Kêng's court. However that may be, he made an agreement of mutual help with Li when the latter was in Foochow, and persuaded him not to join the rebels. With Li on the Manchu side Kêng was in a position to send valuable secret information which Li could relay to the Manchus. It may be surmised that the agreement was really for mutual protectionóshould Kêng be victorious Ch'ên would help Li, and should the Manchus win Li would use his influence to save Ch'ên. In 1675 Li sent a secret memorial to Emperor Shêng-tsu after which his position as a loyal subject became secure. After the collapse of Kêng's rebellion in 1676 Ch'ên begged Li to save him by informing the emperor that the two had collaborated in framing the secret memorial. According to Ch'ên's account Li agreed to do this, but refrained from mentioning Ch'ên's name in the memorial for fear that if the document were intercepted Ch'ên, then in rebel hands, would be endangered. When the two were about to leave for Peking Li's father died and he returned home. Ch'ên proceeded to Peking alone (1678) and there discovered that he was accused by former rebels of having joined Kêng's court. He returned to Fukien and tried in various ways to clear himself, but failed. In 1680 he was arrested as a traitor and, though he pleaded innocent, he was sentenced to death along with Kêng Ching-chung and others. Nevertheless, early in 1682 his sentence and that of three others were commuted to enslavement and banishment. About the same time twenty-five insurgents were executed. Li maintained that he had privately begged the emperor to pardon Ch'ên, and thus was instrumental in saving Ch'ên's life. But Ch'ên was infuriated at Li's failure to report to the emperor that both had a part in drafting the above-mentioned memorial. Soon after his arrival in Mukden where he was exiled, Ch'ên wrote Li accusing him of faithlessness. Their friendship from then on was severed, and Ch'ên repeatedly denounced Li as a traitor.
Ch'ên's life in exile was at first very onerous. The property of his family in Foochow was confiscated and his wife was sent to join him in exile. Then his father, Ch'ên Hui-chieh 陳會捷 (T. 斌侯 H. 賓廷, 1611-1684, Feb.), died. Ch'ên, being now a slave, was compelled to serve certain masters in Manchuria to whom he had been allotted. In the course of time, however, he came to be esteemed as a learned man by the gentry in his place of exile. He became a teacher and learned both to speak and to write Manchu. In 1698 Emperor Shêng-tsu celebrated his victory over Galdan [q.v.] by visiting the tombs of his ancestors near Mukden. Ch'ên managed to be received by the emperor, and owing to his scholarly attainments was pardoned and was brought back to Peking late in that year. There he served the emperor's third son, Yin-chih [q.v.], as teacher and secretary. By 1705 he felt so secure at Court that he determined to reopen his case against Li Kuang-ti, but his memorial was not transmitted by the officials.
While serving in the household of Yin-chih Ch'ên Mêng-lei began to compile a classified encyclopedia consisting of extracts copied from various works. In 1701 he persuaded Yin-chih to finance the project further so that the encyclopedia would include as many excerpts as possible. These Ch'ên selected and classified with the help of a number of copyists. For source-material he drew on his own library and that of Yin-chih--the two collections amounting to some fifteen thousand chüan. This work began in November 1701 and the first draft was completed in May or June 1706--according to a letter which Ch'ên wrote to Yin-chih on the last-named date. In this letter Ch'ên reported on his scheme of classification and on the work that had up to that time been accomplished. He called the encyclopedia Hui-pien 彙編. Along with his letter he submitted a table-of-contents and a statement of the general purpose of the work, for presentation to Emperor Shêng-tsu. He hoped thus to gain the emperor's approval for  the undertaking, and permission to use the imperial library for further reference. In the same letter he requested seven or eight months' leave on the ground that he had not been to his home in Foochow for twenty-seven years. He added that he was experiencing the first signs of old age and hoped to visit the tomb of his parents who had died in his absence. The leave was probably granted, for Ch'ên was by this time so highly regarded that he was several times favored with the emperor's personal poems and handwriting.
Little is known about Ch'ên Mêng-lei and his encyclopedia during the years 1706 to 1722. Probably Emperor Shêng-tsu became interested in the work, for he gave it the title, 彙編古今圖書集成 Ku-chin t'u-shu chi-chêng, "Synthesis of Books and Illustrations of Ancient and Modern times";. The work seems to have become a state enterprise, for officials were appointed to help Ch'ên in the compilation. One of these assistants was Yang Kuan 楊綰 (T. 子崑 H. 栗齋), who was in charge of the sections on music (樂律) and the "study of characters" (字學). Yang's service on the project began in 1716 and lasted eight or nine years. The enormous enterprise, including as it did many maps and illustrations, was completed before the death of Emperor Shêng-tsu (December 20, 1722). The printing was done from "engraved [ Movable]copper type" (刻銅字), and perhaps by 1722 had been some time under way. But all the evidence relating to this phase of the project was sedulously destroyed by Yin-chên[q.v.] when the latter succeeded his father to the throne. Having fought a long and bitter struggle against his brothers for the throne, the new emperor relentlessly took revenge on his opponents and their supporters. He had many grievances against Yin-chih and, it may be assumed, also against Ch'ên Mêng-lei for assisting Yin-chih in this literary undertaking. Perhaps Ch'ên had in some way offended him. At any rate, Ch'ên was one of the first victims of the emperor's wrath. On January 18, 1723 Yin-ên iSsŭed a decree condemning him as arrogant and accusing him of lawlessness (see translation of the edict in Introduction to Giles' Index). Though Ch'ên was to be tried the edict clearly indicates that banishment was the least that should be meted out to him and his two sons. When the officials of the Board of Punishments, one of them Chang T'ing-shu [q.v.], sentenced him to exile but released his sons, they were severely reprimanded and degraded. In view of Yin-chên's antagonism to Ch'ên it is likely that he did not survive his second exile. It is said that his remains were interred at his native place but that his descendants lived on in Manchuria.
In the edict ordering Ch'ên's arrest the new emperor demanded that the manuscripts of the Ku-chin t'u-shu chi-ch'êng, till then deposited in Ch'ên's home, be appropriated. A commission headed by Chiang T'ing-hsi [q.v.] was appointed to "revise" it. In order to obliterate all signs of Ch'ên's connection with the work Yin-ên cleverly gave all the credit to Emperor Shêng-tsu, and no one dared to dissent from that verdict for fear of being accused of slandering the throne. The "revision" was completed in 1726, and the first edition of the encyclopedia comprising 10,000 chüan, plus a table-of-contents in 40 chüan, was printed in 1728. Sixty-four sets were officially printed, and perhaps several others which the printers may have sold on their own account. In its final form the encyclopedia seems to have differed but little from Ch'ên's draft. Yin-ên claimed that the "revision" involved several hundred thousand characters, which even if true would constitute less than one per cent of the total number which is estimated to be about one hundred million. A second edition of 1,500 sets was printed from movable leaden type by Major Brothers in Shanghai in the years 1884-88. This smaller and less expensive edition is, however, marred by errors. In 1890 the Tsung-li Yamen obtained permission to reproduce the original edition lithographically. One hundred sets of this third edition were prepared in 1895-98 by the T'ung-wên Shu-chü 同文書局 of Shanghai at a cost of 3,500 taels each. Before preparing this third edition, the original was collated by a group of scholars, and these collation notes (校勘記 Chiao-k'an chi), in 24 chüan, were appended to the new edition. The Library of Congress has one set of it presented by the Chinese Government in 1908 in recognition of the remission by the United States of a portion of the Boxer Indemnity. An English index to the encyclopedia, with a valuable introduction, was compiled by Lionel Giles, under the title An Alphabetical Index to the Chinese Encyclopedia, Ch'in-ting (欽定) Ku-chin t'u-shu chi-ch'êng. It was published in London in 1911.
Ch'ên Mêng-lei left a work on the Classic of Changes, entitled 周易淺述 Chou-i ch'ien-shu, 8 chüan. It was written in 1694 and is mentioned in the Ssŭ-k'u Catalogue (see under Chi Yün). Several collections of Ch'ên's literary works are referred to by bibliographers, namely: 天一道人集 T'ien-i tao jên chi, 100 chüan ; 日省堂詩文集 Jih-shêng t'ang shih-wên chi, 1 chüan ; 閑止書屋 (堂) 集鈔 : hsien-chih shu-wu (t'ang) chi-ch'ao, 2 chüan, (printed in 1693?); and 松鶴山房集 Sung-ho shan fang chi, comprising his prose in 20 chüan and his verse in 9 chüan. Two incomplete copies of the Sung-ho shan fang chi are listed in recent cataloguesóone in the Peking National Library (2 chüan missing) and another in the Kuo-hsüeh Library at Nanking.
Ch'ên Mêng-lei had two younger brothers, Ch'ên Mêng-hsiung 陳夢熊 and Ch'ên Mêng-p'êng 陳夢鵬 , the latter a hsiu-ts'ai of 1683. One source asserts, perhaps erroneously, that he had a brother named Ch'ên Mêng-ch'iu 陳夢球 (T. 二受 H. 遊龍, a chin-shih of 1694), who was a member of the Chinese Plain White Banner. According to the Jung-ts'un yü-lu, hsü-chi (see under Li Kuang-ti), the last-mentioned belonged to a family which had been forced to become bannermen because of cooperation with Chêng Chêng-kung [q.v.].
[ 3/116/42a; 4/44/15b; 17/1/63a; 34/104/9a; Ch'ên Shou-ch'i [q.v.], Tso-hai wên-chi 3/40a;國朝文匯 Kuo-ch'ao wên-hui 甲集 , 25/la; Fukien t'ung chih (1922) 列傳文苑清 1/9a, 藝文 61/13b; Tai Tzŭ戴梓, 耕煙草堂詩鈔 Kêng-yen Ts'ao-tíang shih-ch'ao (in 遼海叢書四集) 1/6b, 2/lb, 4/13a; Jung-ts'un p'u-lu ho-k'ao (see under Li Kuang-ti) 上 /37a; Tung-hua lu, K'ang-hsi 21:1, 61:12;詞林輯略 Tz'ŭ-lin chi-lüeh 2/18a; Jung-ts'un yü-lu, hsü-chi, passim;故宮殿本書庫現存目 Ku-kung tien-pên-shu-k'u hsien-ts'un-mu 類書, la;史料旬刊 Shih-liao hsün-k'an, no. 14, p. 天 515; Giles, Index;桐鄉縣志 Tíung-hsiang hsien-chih (1882) 15/ 宦績 4Ob;圖書館學季刊 T'u-shu-kuan hsüeh chi-k'an, vol. 2, no. 2 (1928), pp. 235-45;晚晴簃詩匯 Wan-chíing i shih-hui 36/28a.]