Claude Dariot was a 16th century French astrologer who influenced the way in which aspects were being evaluated when he presented his method of “moities” in his 1558 text L’introduction au jugement des astres (translated into English as Introduction to the Judgement of the Stars). William Lilly refers to Dariot’s system and the use of “moieties” of the orbs of planets. By “orb” Lilly meant the arc of influence of a planet as measured forward or backward from its zodiacal position (what Dariot refers to as “beams”), in other words, the radius of the planet’s sphere of influence. Lilly’s use of the term “orb” differed from an older usage of the term to refer to the diameter of the sphere of influence of the planet. By Lilly’s time it was common to use the term “orb” to refer to the radius of the planet’s sphere of influence rather than to its diameter, though both usages of the term “orb” can be found in the literature.
Here is a relevant page from Dariot’s text:
Transcribing and modernizing a bit the above text:
Of the applications and separations of the Planets.
Chapter VI
“The application happens when the Circles or beams of the Planets come to join together by a corporal Conjunction, or by aspect of the one half of the Diameters:
or when one Planet is distant six degrees from a true aspect to another, or that he do join unto another by the half of his beams.
These Circles or Radiations are diverse and different one from another, because the one is great and the other, little.
For Saturn casts his beams circularly, 9 degrees forward, and so much backward, wherefore the half-diameter of his radial circle contains 9 degrees, and the whole Diameter 18 degrees.
The radial circle of Jupiter is of the same quantity and bigness.
But the circle of Mars contains in his Diameter only 16 degrees, which is 8 degrees for his half.
The Sun casts his beams in compass 15 degrees upon every part, which makes the whole Diameter of his Circle to contain 30 degrees, and the one half, 15 degrees.
Venus and Mercury cast their circular beams 7 degrees every way in length, so their whole Diameter is 14 degrees.
Finally, the Moon sends forth her beams on every side 12 degrees, for the half of the Diameter, and the whole [Diameter] contains 24 degrees.
Then, the right application of the Moon unto Saturn by a sextile aspect shall be when as between the center of their two bodies there is contained 49 degrees and 30 minutes, or at most 54 degrees.
The left application, when as between the two centers is contained 70 degrees and 30 minutes, or at the most 66 degrees, for so much as the moitie of the half-Diameter [that is, the moitie (half) of the Radius] of the Circle radiant of Saturn is 4 degrees 30 minutes, and the half of the Circle of the Moon is six degrees, if then these parts be joined together, which amount to 10 degrees 30 minutes [that is, 4d 30m + 6d = 10d 30m] and taken from 60 degrees [sextile] for the right application, or added unto the same number for the left, the application will easily be found.
Likewise must you judge of all other aspects of the Planets.”
END OF QUOTE FROM DARIOT.
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In plain English:
Dariot quotes the traditional literature that each planet has an orb or sphere of influence, which has a particular diameter and radius. The planet radiates beams from its body in all directions, and the influence of these beams extends a distance measured by the radius of its sphere (orb) of influence.
For example, the diameter of the sphere (orb) of influence of Saturn is 18 degrees. The radius of this orb is 9 degrees. and the beams that radiate from the body of Saturn are influential up to 9 degrees in all directions from the body of Saturn.
Dariot proposes using a system of “moities” (aka, moieties) to measure how far apart planets must be to separate from influencing each other. He may have felt that the traditional method of using orbs was too generous, or too unwieldy because of the large variation in orbs, to determine when planets were continuing to influence each other by aspect, so he decided to break with tradition and try something different.
“Moitie” means the exact half-measure of something, as in taking a length and dividing it precisely in two.
He proposes, for each planet, finding “the MOITIE of the half-Diameter of the Circle radiant” of the planet, that is finding HALF [the moitie] of the RADIUS [the half-Diameter] of the Circle of beams [sphere or orb of influence] that radiate out from the body of the planet. Note that half the radius is a quarter of the diameter of the sphere or orb of influence of the planet.
For example, the sphere (orb) of influence of Saturn is 18 degrees. The radius (half-diameter) of this orb is 9 degrees, and the moitie of the half-Diameter (that is, the moitie of the radius, or half the radius) is 4 degrees 30 minutes.
You then add the moitie of Saturn (which is half the Radius, or a quarter of the Diameter of the orb of incluence) to the moitie of any other planet which aspects Saturn to determine the maximum distance between the two planets at which the aspect will still be within effect. The accompanying table shows the Diameter, Radius and Moitie of the Radius of each of the traditional visible planets.
| Planet | Diameter of the Orb of Influence with the body of the planet at its Center (degrees) | Half-Diameter of the Orb of Influence = the Radius of the Orb (degrees) | Moitié of the Half-Diameter of the Orb of Influence = Half the Radius = 1/4 of the Diameter (degrees) |
| Saturn | 18 | 9 | 4d 30m |
| Jupiter | 18 | 9 | 4d 30m |
| Mars | 16 | 8 | 4 |
| Sun | 30 | 15 | 7d 30m |
| Venus | 14 | 7 | 3d 30m |
| Mercury | 14 | 7 | 3d 30m |
| Moon | 24 | 12 | 6 |
Dictionary Definition of Moitié
L’une des deux parties égales d’un tout:
One of two equal parts of a whole.
Here is the original French text (1558) from google books:
Note the line next to the red arrow, which reads “pource la moitié du demy diamètre du cercle radial de Saturne est de quatre degrés et trente munutos….” or in English “for the moitié of the half-diameter of the radial circle of Saturn is 4 degrees and 30 minutes…”
Here Dariot is stating that the moiety is half the radius of the circle, that is, half of the half-diameter (half of the demy diametre or radius) of the circle surrounding Saturn.
Anthony Louis - Astrology & Tarot Blog 
do you think they used such large orbs compared to nowadays because they weren’t very sure of the exact positions of planets ?? ? Or was there some reason now not considered useful ?
The traditional idea was that planets were surrounded by an orb or sphere of influence filled with the light emitted from the planet at the center of the sphere. Some planets emitted more light than others and therefore had larger orbs (sphere of light surrounding them). There was an ancient theory that eyes emit light which is then reflected back to them in order to allow them to see objects at a distance. The Sun was clearly the brightest body in the heavens, so it had the most far-reaching orb. All other celestial objects “disappeared” as they got close the the Sun. Their ability to remain visible near the Sun was an important determinant of how their orb of influence was measured. Also important was the relative speed of the planet in its orbit around the Earth (geocentrically).
Nowadays modern astrologers associate orbs with aspects rather with the planets, which would have been a strange idea to a classical astrologer who assigned orbs (spheres of influence) to the planets and viewed “aspects” simply as different ways in which the planets could look at each other.
TA plus yes indeed strange . reasons for delineation lost for convenience. this bites your bum when you dont notice things WILL affect one “early”…..