Career
He commanded a unit of 500 soldiers during the Korean War of 1592-1598. In recognition of his military valor, he was awarded a lifetime pension by the Wanli government, which was to continue to be paid to his heirs in perpetuity. During peacetime, he became renowned as an expert on "divination", id est (that is) astrology and geomancy.
In the meantime, in 1601 the Jesuits Matteo Ricci and Diego de Pantoja became the first Christian missionaries to be settled in the Ming capital.
They appreciated Confucian learning and wanted to establish good relations with the Chinese literati, but strongly disparaged the "ridiculous wizardry" of Chinese occult practices. Once Li became a Christian, it took him, Ricci, and de Pantoja three days to go through his "beautiful and well stocked library" to identify all books and manuscripts "forbidden by ecclesiastical regulations".
This apparently was not an uncommon practice in Ricci"s day: when another celebrated convert, the mathematician Ignatius Qu Taisu (瞿太素. Chiutaiso in Ricci"s transcription) became Christian, he also sent his library of books on "the dogma of the sects" to the Nanjing Mission House to be burned, along with book printing plates and non-Christian religious statues.
He proselytized among his friends and families, and got all his servants to join the church as well.
As a person highly knowledgeable about the "sect of idol worshippers", Li was able to supply the Jesuits with a large amount of information that they found helpful in converting other non-Christians.
