BaZi: ZPSYJY - Year, Month, Day and Hour pillars and the period of life

Lately, I've been studying a book written in Ming dynasty called  子平四言集腋 (ZiPing SiYan JiYe), where all the information are written into four words sentences. It's very similar to SYDB but it explains a lot more than that cryptic poem. Still it is a very strange book.

This excerpt is taken from that over 500 years old book.

年月主初, 共年廿五, 气未大舒, 日为中限, 二十五年, 时为末限, 五十年全

Year and Month represents the Early (time of life), a total of 25 years (old), where the Qi is yet greatly unfold, Day as the middle boundary, 25 years (of age), Hour as the eventual boundary, a complete of 50 years (old)

In summary,

Year + Month pillar -- Below 25 years old --- known as early boundary 初限
Day Pillar -- Between 25 to 50 years old --  as middle boundary 中限
Hour Pillar -- Above 50 years old -- as eventual (final) boundary 末限