BaZi: 月令 Month command

Yue Ling

The term YueLing 月令 is made of 2 words, Yue 月 which means month and Ling 令, which means command. Historically, YueLing refers to the different proceedings of the government for different months through the year. Such was recorded in 礼记，The book of rites written around 200 BC. 令 'command' refers to the command from the government to the pheasants to carry out certain activities such as sowing, harvesting, repairing castle wall etc etc.

In Bazi, YueLing refers to the month commander, the entity that takes charge during a certain period of the month. There are 12 months in Bazi, beginning with Yin, which also marks the beginning of spring to Chou, which marks the end of the year. From Yin to Chou, the Yin and Yang of the 5 elements take turns in ruling the month.

SMTH writes:

轻清者为十干，主禄，谓之天元，

The ones that are light and pure are the 10 stems, they represent 'fortune', named as Heavenly Origin

重浊者为十二支，主身，谓之地元，

The ones that are heavy and mixed are the 12 branches, they represent 'body', named as Earthly Origin

天地多正其位，成才于两间者，乃所谓人也。

The ones that reside and work between heaven and earth are human.

故支吕所藏者主命，谓之人元，名为司事之神，以命术言之为月令

Thus, the ones stored inside the branches are called Human Origin, its name is the God that takes charge, from the art of life perspective, the name is Month Command.

Solar Terms

To understand the concept of YueLing, knowledge about the 24 Solar Terms is necessary. Solar Terms were used by the ancient Chinese to mark certain astronomical or natural event that happens through the year. A year is divided into 4 seasons 季，each season is divided into 6 terms 节 and each term is further divided into 3 pentads 候。Briefly, there are 4 seasons, 24 terms and 72 pentads in a year.

The table below shows the name of the 24 solar terms and the date they happen. (from wikipedia)

Longi- tude	Usual translation	Chinese name ¹	Japanese name	Korean name ²	Vietnamese name	Date ³	Remark
315°	start of spring	立春 lìchūn	立春 risshun	입춘 (立春) ipchun	Lập xuân	Feb 4
330°	rain water	雨水 yǔshuǐ	雨水 usui	우수 (雨水) usu	Vũ thủy	Feb 19	more rain than snow
345°	awakening of insects	驚蟄 (惊蛰) jīngzhé	啓蟄 keichitsu	경칩 (驚蟄) gyeongchip	Kinh trập	Mar 6	lit. awakening of hibernating insects. See the note at Chinese calendar#Solar term.
0°	vernal equinox	春分 chūnfēn	春分 shunbun	춘분 (春分) chunbun	Xuân phân	Mar 21	lit. spring division (or center)
15°	clear and bright	清明 qīngmíng	清明 seimei	청명 (清明) cheongmyeong	Thanh minh	Apr 5	time for tending graves
30°	grain rain	穀雨 (谷雨) gǔyǔ	穀雨 kokuu	곡우 (穀雨) gogu	Cốc vũ	Apr 20	lit. grain rain: rain helps grain grow
45°	start of summer	立夏 lìxià	立夏 rikka	입하 (立夏) ipha	Lập hạ	May 6
60°	grain full	小滿 (小满) xiǎomǎn	小満 shōman	소만 (小滿) soman	Tiểu mãn	May 21	grains are plump
75°	grain in ear	芒種 (芒种) mángzhòng	芒種 bōshu	망종 (芒種) mangjong	Mang chủng	Jun 6	lit. awns (beard of grain) grow
90°	summer solstice	夏至 xiàzhì	夏至 geshi	하지 (夏至) haji	Hạ chí	Jun 21	lit. summer extreme (of sun's height)
105°	minor heat	小暑 xiǎoshǔ	小暑 shōsho	소서 (小暑) soseo	Tiểu thử	Jul 7
120°	major heat	大暑 dàshǔ	大暑 taisho	대서 (大暑) daeseo	Đại thử	Jul 23
135°	start of autumn	立秋 lìqiū	立秋 risshū	입추 (立秋) ipchu	Lập thu	Aug 8
150°	limit of heat	處暑 (处暑) chǔshǔ	処暑 shosho	처서 (處暑) cheoseo	Xử thử	Aug 23	lit. dwell in heat
165°	white dew	白露 báilù	白露 hakuro	백로 (白露) baekro	Bạch lộ	Sep 8	condensed moisture makes dew white
180°	autumnal equinox	秋分 qiūfēn	秋分 shūbun	추분 (秋分) chubun	Thu phân	Sep 23	lit. autumn division (or center)
195°	cold dew	寒露 hánlù	寒露 kanro	한로 (寒露) hanlo	Hàn lộ	Oct 8
210°	frost descent	霜降 shuāngjiàng	霜降 sōkō	상강 (霜降) sanggang	Sương giáng	Oct 23	appearance of frost and descent of temperature
225°	start of winter	立冬 lìdōng	立冬 rittō	입동 (立冬) ipdong	Lập đông	Nov 7
240°	minor snow	小雪 xiǎoxuě	小雪 shōsetsu	소설 (小雪) soseol	Tiểu tuyết	Nov 22
255°	major snow	大雪 dàxuě	大雪 taisetsu	대설 (大雪) daeseol	Đại tuyết	Dec 7
270°	winter solstice	冬至 dōngzhì	冬至 tōji	동지 (冬至) dongji	Đông chí	Dec 22	lit. winter extreme (of sun's height)
285°	minor cold	小寒 xiǎohán	小寒 shōkan	소한 (小寒) sohan	Tiểu hàn	Jan 6
300°	major cold	大寒 dàhán	大寒 daikan	대한 (大寒) daehan	Đại hàn	Jan 20

From the beginning of spring 立春 to the great cold 大寒。Each of the solar terms has about 15 days more or less. Due to the speed of the earth along the ecliptic (黄道）varies depending on its distance from the sun (because of Earth's orbital eccentricity), some solar terms are longer than the others.

Solar Term and Month Command.

Month command is determined by the day in the Solar Terms when a person is born. This poem from YHZP tells which element has the command by referring to the Solar Terms.

立春念三丙火用，餘日甲木旺提纲。
Lichun, twenty three Bing fire is used, the rest of the days Jia wood is prosperous and the key factor.

惊蛰乙木未用事，春分乙木正相当。
Jing Zhe, Yi wood yet to take command, ChunFen, Yi wood is rightly taking charge.

清明乙木十日管，后来八日癸水洋；穀雨前三戊土盛，其中土旺要消详。
QingMing, Yi wood takes charge for 10 days, after that Gui water becomes ocean for 8 days; GuYu first three Wu earth is prosperous, the things inside the prosperous has to be analyzed.

立夏又伏戊土取；小满过午丙火光。
LiXia, again is taken by Wu earth; XiaoMan after Wu (horse) Bing fire shines.

芒种己土相当好，中停七日土高张；夏至阴生阳极利，丙丁火旺有土张。
MangZhong, Ji earth is really good, stops at the middle 7 days earth rises and expands; XiaZhi is when Yin is born and Yang is at its extreme, Bing and Ding fire are prosperous and earth expands.

小暑十日丁火旺，后来三日乙木芳，己土三日威风盛；大暑己土十日黄。
XiaoShu, ten days Ding fire is prosperous, after that for 3 days Yi wood is frangrant, Ji earth for 3 days is impressively prosperous; DaShu Ji earth is 10 days yellow.

立秋十日壬水涨；处暑十五庚金良。
LiQiu, 10 days Ren water rises; ChuShu, 15 Geng metal is good.

白露七日庚金旺，八日辛兮祇独行。
BaiLu, 7 days Geng metal prospers, 8 days Xin only walks alone.

寒露七日辛金管，八日丁火又水降；霜降己土十五日，其中杂气取无妨。
HanLu, 7 days Xin metal take charge, 8 days Ding fire and water surrenders; ShuangJiang, Ji earth fifteen days, the mixed Qi inside might as well be taken.

立冬七日癸水旺，壬水八日更流忙；小雪七日壬水急，八日甲木又芬芳。
LiDong 7 days Gui water prospers, Ren water 8 days gets busy flowing; XiaoXue 7 days Ren water is in hurry, 8 days Jia becomes fragrant again.

大雪七日壬水管；冬至癸水更潺汪。
DaXue 7 days Ren water takes charge; DongZhi Gui water's sounds of flowing accumulate.

小寒七日癸水养，八日辛金丑库藏；大寒十日己土胜，术者精研仔细详。
XiaoHan 7 days Gui water nourishes, 8 days Xin metal is stored inside storage; DaHan 10 days Ji earth wins, those who practice the art should research in great detail.

There are other versions of this poem. I do not know how they are derived and which is more accurate. At the moment I'm using this YHZP version and it seems pretty accurate to me.

Transformation and change of month command

In Bazi, one should know that HS and EB are made of Qi, Heaven has a focused Qi that is moving 动 and EB is majorly mixed Qi which are still (stationary) 静. When the Qi moves, it takes precedence over 'still' Qi. There are 2 ways for month EB Qi to move.

1. Protrudes in Heaven.
2. Interaction between the branches.

If there are 2 moving Qi from a particular Month EB, one chart will have 2 Commanders. Whether this is auspicious or not will be analyzed from the basics of Follow Use  顺用  or Against Use 逆用.

When there's no change or transformation involved, the original commander dictates by the solar terms remains the commander.

Month command is the YongShen

The final month commander (after transformation or the original) is the YongShen 用神 (refer ZPZQ), which is an abbreviation of the term 用事之神 YongShiZhiShen (refer DTS)  - The God that takes command. The literal translation by modern English bazi 'Masters' - Useful God is misleading because it does not reflect the true identity of this entity.

However, according to the theories in ZPZQPZ written by Master Xu LeWu who distorted Master Shen XiaoZan works - ZPZQ, YongShen is defined as the most needed entity in a chart. Master Xu's works  then give rise to contemporary / modern Bazi which deviates quite a distance from the classics (in my opinion), especially on subject of YongShen.

The use of Month Command, aka YongShen

BaZi is made of layers, each of the layers is analyzed according to the concept of TiYong 体用 - Form and Use.

The first layer takes DM as the Form, and month commander as Use.

The second layer takes the month commander Ti - Form, and then seek for the Yong - Use, according to the concept of ShunYong 'Follow Use' or NiYong 'Against Use'. and the Minister God could be found and the structure can be established.

The third layer takes the structure that is made of DM, Month command and Minister God as Form, other entities in the chart to use.

The fourth layer takes the chart as a whole as the Form, DaYun etc as Use.

In summary, determining the correct Month command is arguably the most important step in analyzing Bazi, which is why the month command is often called 提纲 - the Key Point in almost all literature. It is the focal point of classical Bazi analysis.

Reference:
1. SMTH -论人元司事 Discuss Human Origin taking charge
2. DTS -月令 Month Command
3. ZPZQ - A few chapters about Yong Shen
4. SFTK - 静动说 The saying about movement and stillness
5. The book of rites 礼记 - Month Command
6. Wikipedia - Solar Terms
7. YHZP - the poem about month command.
8. DTS - 体用 Form and Use

For those who are interested to read more about YueLing on LiJi, here's the link

Note: Thanks to duesouth for pointing out the correct name - The book of rites.