A dialogue with deities
At Yinxu, the last capital of the Shang Dynasty (c. 1600-1046 BCE), royal diviners practiced a refined form of pyromancy, or divination by fire. They used the plastrons (flat undershells) of turtles and the scapulae (shoulder blades) of oxen to seek guidance from ancestors and deities. The process began with polishing the shells and bones. Then, diviners chiseled rows of hollows or pits into the reverse side. A question, or "charge," was addressed to the spirits. A heated bronze poker or other fiery brand was then inserted into the hollows. The intense heat produced sharp cracking sounds and a pattern of fissures on the polished front surface; the character for this process, bǔ (卜), resembles one of these cracks. The Shang king himself would often interpret the geometry of these cracks to receive an answer, typically "auspicious" or "inauspicious".
The questions posed reveal the daily anxieties of the Shang court. Rulers asked about military campaigns, harvest yields, upcoming weather patterns, the outcome of royal births, and even the source of the king's toothaches. After the ceremony, scribes would frequently carve the question, the date, the diviner's name, the king's interpretation, and occasionally the actual outcome onto the bone itself, creating a permanent archive of royal concerns.