Yueh Lao — the Old Man Under the Moon — is one of the most beloved figures in Chinese popular religion, a gentle deity whose sole purpose is matchmaking and the protection of romantic unions. He is typically depicted as a benevolent elderly man, often white-bearded, carrying a book in which the fates of couples are recorded and a spool of red thread. The red thread connects two people from birth, running invisibly between them through all the years of their lives until circumstances finally bring them face to face. This concept — that romantic connection is not random but part of a predestined pattern — has been extraordinarily persistent in East Asian culture, and it translates easily across modern contexts: the Japanese say "red string of fate" (unmei no akai ito), and the idea has spread far beyond its Chinese origins.

The story behind Yueh Lao comes from a Tang Dynasty tale in which a traveler named Wei Gu encounters a mysterious old man sitting beneath the moon, consulting a large book. The old man explains that this is the Book of Marriages, and that he uses red thread to tie together the feet of those who are destined to wed. Wei Gu is skeptical, but the old man's predictions prove entirely accurate. The story encapsulates what people have always wanted to know about love: whether it is arbitrary or meaningful, whether there is a plan or only chance. Yueh Lao doesn't promise that love will be easy, or that the person you're meant to meet will arrive on schedule. He simply holds the thread, tends the book, and works quietly in the background. Temples dedicated to him — particularly in Taiwan and Fujian — are perennially busy with people seeking his counsel on matters of the heart.