In the winter of 5 AD, Wang Mang gave pepper wine (considered in those days to be capable of chasing away evil spirits) to the 14-year-old emperor, but had the wine spiked with poison. As the emperor was suffering the effects of the poison, Wang Mang wrote a secret petition to the gods, in which he offered to substitute his life for Emperor Ping's, and then had the petition locked away. Historians generally believe that Wang Mang had two motives in doing this—to absolve himself of involvement in the poisoning if Emperor Ping recovered from the poisoning, and to leave evidence of his faithfulness for posterity.