Controversies and Blind Spots of Zi Wei Dou Shu
(1) Due to the calculation method of years and months in Zi Wei Dou Shu, which does not use the 24 solar terms, there are differing opinions on how to calculate leap months. Some advocate using the current month for calculations, while others suggest using the following month. There are also those who propose that dates before the 15th should be governed by the previous month, and dates after the 15th should be governed by the following month.
(2) Regarding the calculation of days in Zi Wei Dou Shu, some argue that midnight (0:00) is the dividing line, with everything after midnight considered as part of the current day until 23:59:59 of that day. If it crosses back to midnight again, it is then considered as belonging to the next day. Others contend that 23:00 is the dividing line; anything before this time belongs to the current day, while anything after 23:00 belongs to the next day.
(3) The late hour of Zi (between 23:00 and 24:00) is a focal point of controversy because if charts are calculated for the same day, they will be identical to those calculated for early Zi hours. Therefore, individuals born between 23:00 and 24:00 present a particularly perplexing issue.
Note: Those born at exactly the same year, month, and time will only have different positions for their solar stars; everything else remains identical—this presents a significant blind spot in Dou Shu.
by – Dou Shu Arena