Ghép mười hai quẻ tiêu tức (phục, lâm, thái… khôn) với mười hai tháng để định hỏa hầu luyện kim đan. Vừa mang tính thuật số/dịch lý vừa là bí quyết hỏa hầu ngoại/nội đan theo chu kỳ năm.
Ứng dụng: Định hỏa hầu theo tháng–quẻ; tham chiếu luyện đan và lịch pháp.
外丹火候專書，原題玄和子（或謂唐張太空），正一部。以十二消息卦配十二月與十二時，論還丹文武火：復卦（十一月子）一陽初生、子時順天罡起符；臨、泰、壯、夬至乾（午）陽長武火；姤起一陰，遁、否、觀、剝至坤（亥）陰長文火、添水護鼎。術語：青龍（汞）、白虎（金鉛）、赤龍、紫粉、紅蓮、紫遊丹、海（水鼎）、城（爐）。強調「年象月亦象，唯日時是訣」，攢簇陰陽於一室；批判時人但學胎息而不知紫遊大丹。為參同契系卦氣火候的歌訣化總結。
⚡ Ứng dụng: 外丹（及部分內丹火候借喻）按月卦進退火：冬至復起文火，夏至乾極轉姤收火，坤滿開鼎取紫粉。可與參同契、火記合參。
🔗 Liên quan: 周易參同契；金丹大要；丹房須知
This work proves that the twelve monthly hexagrams (message of waxing/waning yang) are a golden operational key for timing alchemy and action: microcosmic fire phases must lock to macrocosmic month-gua, or effort fights the season’s vector.
1) Overlay the twelve month gua on the BaZi annual/monthly branches (e.g. midwinter 復 = Zi month) when planning retreats. 2) Increase collecting practices in yang-rising months (丑–巳 direction of the cycle) and emphasize storing/protecting in yang-falling months. 3) For chart holders with weak yang Day Masters, never force peak fire work in 剝/坤 seasonal phases. 4) Use the金訣 maxims as checklists before opening the furnace (literal or physiological). 5) Journal month-gua vs. body signs (cold/heat, libido, clarity) to personalize the key.
Unlike raw Yijing monthly gua lists or general 節氣 health advice, this text claims a ‘golden key’—operative compression for neidan/waidan timing. It differs from pure BaZi ten-god monthly luck by using hexagram vectors of pure yang measure rather than stem-branch social/functional gods; the why is alchemical isomorphism of cosmos and furnace.