In Chinese numerology, the number nine is associated with the principal of Yang, the masculine complement of Yin in the Yin/Yang system. Today is the ninth day of the ninth month in the Lunar-Solar calendar (hence the name “Double Yang/Double Brightness”). While Yang is generally considered a good thing, too much of anything can throw a system out of balance. When systems are out of balance, as the 84-year-old auntie who lives on your hutong will remind you every day this winter, people get sick.