The main feature of this membership certificate of the Tsung Sin Kongsi, a Hokkien secret society in Singapore that emerged from the Tiandihui (Heaven and Earth Society), is the octagon inscribed with the teachings of the society and a three-sided numerical puzzle on the top of the inner octagon containing symbols which represented numbers adding up to 15 as read from whichever direction. The local version of the Tiandihui originated from the secret society in China, a sworn fraternity comprising Chinese men with the common aim of overthrowing the Qing dynasty and restoring the Ming. With increased Chinese migration to Singapore, the local society became a form of mutual-aid and support, and various splinter groups (hui or kongsi) subsequently emerged among the main dialect groups.
