Zi Collection, Upper Volume, Page 45, Entry 02 In the "Jiyun" (集韵), it is recorded that the character "lei" (雷) was written as "䨓" in ancient times. See the five-stroke section for detailed notes. The "Yunhui" (韵会) quotes the "Tongzhi" (通志) saying that the character "hui" (回) is the ancient character for "䨓", and later people added the "rain" radical on top to write "䨓". The character "hui" symbolizes the shape of thunder, and ancient vessels like "zun" (尊) and "lei" (罍) were often decorated with cloud patterns and "hui" patterns.