What is the main reason for compiling Sikuquanshu? Where were these seven original works collected at that time?

In November of the thirty-seventh year of Qianlong (1772), Zhu Jun, an Anhui scholar, put forward the issue of compiling Yongle Dadian, which was recognized by Emperor Qianlong. Later, the imperial edict compiled the lost books based on the standard of "collected by the provinces and engraved by the officials of Wuyingtang", which was called Sikuquanshu. In this way, the compilation of Yongle Dadian led to the huge project of compiling Sikuquanshu, which became the direct reason for compiling Sikuquanshu. The compilation process of Sikuquanshu is divided into four steps: the first step is to collect books. The collection of books lasted for seven years from the thirty-seventh year of Qianlong (1772) to the forty-third year of Qianlong (1778). In order to commend those who entered the book, the Qing court also formulated methods such as giving books, chanting scriptures and registering names. : "Award Book" means that those who are shortlisted for more than 500 books will be given a book "Integration of Ancient and Modern Books"; Those who read more than 100 books will get a copy of Pei Yunwen Fu. "Inscription" means that those who have entered more than 100 kinds of books choose a pure and mellow book, and Emperor Qianlong will inscribe it on the short side to show his favor. "Registration" means to indicate the name of the collector or book collector in the abstract. With the strong assistance of the local government and the positive response of bibliophiles, the collection of books is progressing smoothly, with a collection of12,237 volumes, including 4,808 Jiangsu books, ranking first in all provinces. Zhejiang has 4600 books, ranking second. Private book collectors such as Ma Yu, Bao Shigong, Fan Hewang have also entered many books.

The second step is to organize books. In order to collect Sikuquanshu, Emperor Qianlong modeled the famous library "Tianyi Pavilion" and built seven pavilions in the north and south respectively. Forty-six years after Qianlong (178 1), the first Sikuquanshu was finally copied and bound. Then it took nearly three years to copy the second, third and fourth books and store them in Wen Yuan Pavilion, Wenshui Pavilion, Wen Yuan Pavilion and Jinwen Pavilion. This is the so-called "North Four Pavilion". From July of the forty-seventh year of Qianlong (1782) to the fifty-second year of Qianlong (1787), three more copies were copied and stored in the collections of Wenzong Pavilion, Wenhui Pavilion and Wen Lan Pavilion in the south of the Yangtze River. This is the so-called "Nansange". Each Sikuquanshu has 36,300 volumes and 6,752 letters. All the books in the seven museums have seals, such as the seal of the first Zhu in the collection and the seal of the last Zhu.