Commanding and obeying signs

Meaning

Two signs are commanding and obeying when they lie the same distance on either side of an equinox, the start of Aries or the start of Libra, where the Sun crosses the celestial equator. One sign of each pair is north of the equator and the other south, by the same amount.

Two things follow. First, the two signs take the same time to rise over the eastern horizon, wherever the observer is. Second, the Sun makes them mirror images in the calendar: the length of the day when the Sun is in one equals the length of the night when it is in the other. Ptolemy gives the first reason, adding that the signs lie on "equal parallels" (the same distance from the equator). He names the northern sign of each pair commanding and the southern one obeying, because the Sun in the northern half makes the day longer than the night, and in the southern half shorter [1].

Measured degree by degree from the equinox points, the pairs are:

The degrees correspond in reverse: 10° Taurus goes with 20° Aquarius. A degree's partner is its contra-antiscion (contra-antiscion).

Origin and history

Ptolemy. The Tetrabiblos defines these signs in Book I, chapter 14 in Robbins's numbering (chapter 17 in Ashmand's older translation [4]), as the divisions of the zodiac an equal distance from the same equinoctial sign [1]. Like the signs of equal power, they are counted in whole signs. Robbins lists the pairs, commanding sign first, as Taurus–Pisces, Gemini–Aquarius, Cancer–Capricorn, Leo–Sagittarius and Virgo–Scorpio. Aries and Libra, the equinoctial signs from which the count starts, are left out, as they are in Manilius [1]. Robbins also suggests the older idea was that these signs "hear" each other, and that "obeying" (a compound of the Greek verb for hearing) was a later elaboration [1].

Al-Bīrūnī. In 1029 al-Bīrūnī measures from the equinoctial point itself. Two signs equidistant from it are "equipollent", or agree in power. The day hours of each equal the night hours of the other, their ascensions are equal in all places, and the correspondence runs by inverse degrees, one sign north and one south. His examples are Aries with Pisces and Taurus with Aquarius, the first degree of Aries matching the twenty-ninth of Pisces [2]. He reports that Abū Ma'shar treated Aries–Pisces and Virgo–Libra, neighbours that do not see each other, as "natural sextiles"; Gemini–Capricorn and Cancer–Sagittarius as "natural opposites"; and held that the bond softens the square between Taurus and Aquarius or Leo and Scorpio [2].

A reversed usage. In the next section al-Bīrūnī uses "obedient" in another sense. The "crooked" signs of short ascension, Capricorn through Gemini, obey. Of two signs on the same parallel, the one from the half Cancer–Sagittarius comes first in the daily turning of the sky, and so commands the other, which always follows [2]. That pairing runs across the solstice axis, not the equinox axis. Wright's notes contrast it with Ptolemy's scheme: Chaucer too calls the crooked signs obedient to the signs of long ascension, while, according to Wright, the southern signs were formerly called obedient, as in Ptolemy, in a diagram printed in a 1586 edition of Paulus Alexandrinus, and in Valens [2]. (The Paulus and Valens passages were not checked directly for this article.) Readers of older texts should check which scheme an author means.

Lilly. Lilly lists the commanding signs as Aries through Virgo and the obeying signs as Libra through Pisces, Ptolemy's northern and southern halves, and says no more about them there [3]. On the same page he defines the "contrantiscion" as the point opposite a planet's antiscion [3]. That point is the same degree as the planet's partner across the equinox axis.

Placidus. In 1657 Placidus applied the names degree by degree. For him antiscia are "parallels", points of equal declination; when the two lie on opposite sides of the equator, "the northern commands, the southern obeys" [5].

How it is used

The relation survives mainly as the contra-antiscion: a planet's mirror degree across the equinox axis, 360° minus its longitude. Lilly likens contrantiscions to a square or opposition [3], so the partner across the equinox axis is often read as a hidden tension rather than the friendly link of the antiscion; see contra-antiscion for other views.

Because paired degrees lie the same distance north and south of the equator, the relation is the ecliptic form of a declination contra-parallel (see declination parallel). This is exact only for points on the ecliptic.

On this site. The Antiscia panel lists each point's contra-antiscion (360° minus its longitude) and reports contacts across the equinox axis within the chosen orb, 1° by default. For each contact it says whether the two points are also truly contra-parallel in declination, and if not, names the points that lie off the ecliptic. The panel does not label either partner as commanding or obeying.

Examples

• 10° Taurus and 20° Aquarius. Declinations about 14°49′ north and 14°49′ south. At London's latitude (51.5° N), ignoring refraction, the day at 10° Taurus (about 30 April) lasts about 14 h 35 m, and the night at 20° Aquarius (about 9 February) lasts the same.
• Equal rising times. At 51.5° N, the whole of Aries takes about 53 minutes to rise, and so does the whole of Pisces. Virgo and Libra each take about 2 hours 51 minutes.
• Mars at 5° Leo. Its contra-antiscion is 25° Scorpio. In the degree-by-degree pairing Scorpio is Leo's obeying partner; in Ptolemy's whole-sign pairing Leo's partner would be Sagittarius.