Orbs & Moieties

Orbs and Moieties in Traditional Astrology

Al-Biruni, Dariot, Lilly, and Why a Jupiter–Venus Aspect Does Not Simply Have “One Fixed Orb”

In modern astrological practice, an aspect is often treated as though it possesses its own fixed tolerance. A trine may be assigned an orb of 8°, a sextile 5°, an opposition 8° or 10°, and so forth. The astrologer measures the distance from exactitude, compares it with the permitted orb, and decides whether the aspect exists.

Traditional astrology approaches the problem differently.

In the medieval and Renaissance traditions, orbs fundamentally belong to planets rather than to aspects. The allowable distance between two planets therefore depends upon which planets are forming the aspect. A Jupiter–Venus trine, a Moon–Venus trine, and a Sun–Venus trine need not begin operating at the same distance from exact perfection even though all three are trines.

This distinction is one of the most important differences between traditional and modern aspect doctrine.

The traditional system also introduces a second concept: the moiety, or half-measure of a planetary orb. By combining the moieties of two planets, the astrologer can determine the effective distance at which their rays begin to interact.

Yet even this apparently simple rule has a complicated history. Al-Biruni records several competing approaches to planetary influence; Claude Dariot gives one of the clearest Renaissance formulations of the combined-moiety method; and William Lilly inherits both the method and the disagreement over the proper numerical values of the planetary orbs.

Understanding these distinctions is essential for anyone attempting to practice horary, electional, natal, or mundane astrology according to traditional principles.

1. The Traditional Idea of an Orb

The word orb can mislead the modern reader because it is frequently imagined as nothing more than a numerical tolerance attached to an aspect.

Historically, the concept is more physical and planetary.

A planet was understood to extend rays, virtue, or influence beyond its visible body. Its influence therefore occupied a region around its zodiacal position. The traditional literature speaks of planetary rays, beams, circles, or spheres of influence.

The Sun and Moon, as the luminaries, possess especially extensive influence. Mercury and Venus have substantially smaller ranges. Mars is somewhat larger, while Jupiter and Saturn are traditionally granted more extensive rays than the inferior planets.

A commonly transmitted medieval set of planetary values is:

These figures are recorded in connection with Al-Biruni and recur widely within later traditional astrology. Earlier material also preserves essentially the same sequence of planetary rays.

Immediately, one consequence becomes apparent:

A traditional aspect does not possess an orb independently of the planets creating it.

The trine itself does not inherently “have an 8° orb.”

Neither does the square inherently possess 6°, nor the sextile 4°.

Instead, Venus brings one radius of influence, Jupiter another, the Moon another, and the Sun another.

The planets determine the field within which the geometrical aspect becomes effective.

2. Orb, Radius, Diameter, and a Terminological Trap

Traditional texts can become confusing because the word orb has not always been used with exactly the same geometrical meaning.

Suppose Jupiter casts its rays 9° before and 9° after its body.

Its entire circle of zodiacal influence therefore measures:

9° + 9° = 18°

A writer may describe 18° as the entire diameter of Jupiter’s orb.

Another may simply say that Jupiter “has an orb of 9°,” meaning the radius extending from the planet in either direction.

Dariot’s geometrical explanation is particularly useful. His radial circle for Jupiter and Saturn extends 9° from the planetary body in either direction, producing an 18° diameter. Mars extends 8° on each side, the Sun 15°, Venus and Mercury 7°, and the Moon 12°.

Modern traditional astrologers usually simplify the terminology and list:

Jupiter = 9° orb

rather than:

Jupiter = 18° total diameter / 9° radius.

This convention is perfectly workable provided one understands what the number represents.

The confusion becomes greater when the word moiety enters the discussion.

3. What Is a Moiety?

Moiety means a half or half-part.

Under the Dariot-style system, the planetary value normally quoted as the orb radius is divided by two.

Thus:

The aspectual allowance between two planets is then calculated by adding their respective moieties.

Mathematically:

Effective aspect allowance = Moiety A + Moiety B

Since each moiety is half the planetary orb radius:

Effective allowance = Orb A / 2 + Orb B / 2

or equivalently:

Effective allowance = (Orb A + Orb B) / 2

This is the practical formula most astrologers mean when speaking today of the traditional moiety system. Dariot provides one of the clearest historical descriptions of this approach, explaining that the planets enter effective application when the relevant portions of their rays meet.

4. Why Jupiter–Venus Does Not Simply Have a Fixed Orb

Consider Jupiter and Venus.

Using the widely transmitted Al-Biruni/Dariot figures:

• Jupiter orb = 9°
• Jupiter moiety = 4°30′
• Venus orb = 7°
• Venus moiety = 3°30′

Their combined aspectual allowance is therefore:

4°30′ + 3°30′ = 8°

Alternatively:

(9° + 7°) / 2 = 8°

Consequently, a Jupiter–Venus conjunction, sextile, square, trine, or opposition may be considered within the combined moiety at approximately 8° from perfection, assuming the rest of the traditional aspect conditions are satisfied.

Now compare Venus with the Moon.

Moon:

12° / 2 = 6°

Venus:

7° / 2 = 3°30′

Combined:

9°30′

A Moon–Venus aspect therefore has a substantially greater effective range than Jupiter–Venus.

Now compare Venus with the Sun:

Sun:

15° / 2 = 7°30′

Venus:

7° / 2 = 3°30′

Combined:

11°

Thus the same Venus may enter an effective aspect:

• with Mercury at approximately 7°
• with Mars at approximately 7°30′
• with Jupiter at approximately 8°
• with the Moon at approximately 9°30′
• with the Sun at approximately 11°

The geometrical aspect may remain identical.

The participating planets change.

And therefore the permissible distance changes.

This is the essential traditional logic.

5. Traditional Aspect Distance Is Relational

Traditional astrology therefore treats aspectual contact as a relationship between two planetary powers.

Consider three hypothetical trines:

Mercury trine Venus

Mercury moiety: 3°30′
Venus moiety: 3°30′

Maximum combined moiety: 7°

Jupiter trine Venus

Jupiter moiety: 4°30′
Venus moiety: 3°30′

Maximum combined moiety: 8°

Sun trine Venus

Sun moiety: 7°30′
Venus moiety: 3°30′

Maximum combined moiety: 11°

A modern fixed-orb system might classify all three simply as:

Trine — maximum orb 8°.

The traditional system instead says:

The aspect is a geometrical relationship, but the distance across which that relationship can operate depends upon the planets emitting the rays.

This is a considerably more dynamic model.

6. Al-Biruni: The Tradition Was Never Completely Uniform

Abu Rayhan al-Biruni’s Book of Instruction in the Elements of the Art of Astrology, written in the eleventh century, is exceptionally important because it demonstrates that medieval astrologers were already dealing with competing theories concerning aspectual limits.

The familiar values associated with Al-Biruni are:

Sun 15°, Moon 12°, Mercury 7°, Venus 7°, Mars 8°, Jupiter 9°, Saturn 9°.

But one should not turn Al-Biruni into the author of a rigid universal “moiety law.”

The historical situation was considerably less uniform.

Al-Biruni reports that astrologers used several approaches to the limits of planetary configurations. Some employed approximately the Moon’s 12° range; others used the Sun’s 15°; others considered the mean influence of the two planets involved. Other systems employed smaller universal values such as 5° or 6°.

This is critically important.

Traditional astrology was not a monolithic software specification.

Astrologers inherited competing authorities, astronomical theories, practical conventions, and regional schools. The numbers that modern practitioners sometimes describe as “the traditional orbs” are better understood as a particularly influential transmitted set rather than the only values ever used historically.

Al-Biruni therefore teaches us two things simultaneously:

1. Planetary influence was individualized according to the planet.
2. The exact method by which those influences determined aspectual contact remained debated.

This historical caution becomes particularly important when later authors are compared.

7. Dariot and the Systematic Moiety Method

Claude Dariot, the sixteenth-century French physician and astrologer, provides one of the clearest Renaissance descriptions of the system modern traditional astrologers usually mean by moieties.

Dariot describes the planets as possessing circles or radiations through which they may unite either bodily by conjunction or through aspect.

Using essentially the familiar planetary values, he gives:

• Saturn: 9° radius
• Jupiter: 9°
• Mars: 8°
• Sun: 15°
• Venus: 7°
• Mercury: 7°
• Moon: 12°

Dariot then divides these radii to obtain the moieties involved in determining application.

For example, Mercury contributes:

7° / 2 = 3°30′

The Moon contributes:

12° / 2 = 6°

Therefore Mercury and the Moon enter their effective combined range at:

9°30′ from exact aspect.

Dariot’s presentation is valuable because it converts the general idea of planetary rays into an operational procedure.

The planets do not merely possess abstract spheres of influence.

Their respective ranges determine when their relationship begins to become dynamically operative.

8. Application, Perfection, and Separation

Orb should not be confused with perfection.

Suppose Jupiter is applying to a trine with Venus.

The exact trine occurs at 120°.

With the standard moiety calculation, Jupiter and Venus may enter effective aspectual contact when they are within approximately 8° of exactness.

Their relationship therefore passes through several stages.

Outside the combined moieties

The planets may be geometrically approaching the aspect, but the effective contact has not yet fully formed according to the moiety criterion.

Entry into moiety

The planetary rays begin to meet.

The aspect becomes operational.

Applying within orb

As the planets approach exactitude, the configuration becomes increasingly immediate.

Perfection

The aspect becomes exact.

This is the culmination of the application.

Separation

Once the faster planet has passed exactitude, the configuration begins separating.

Its influence does not necessarily disappear instantly. It remains within the relevant range until the planets move sufficiently far apart.

Dariot explicitly connects the combined moiety with this process: recognisable effect increases as perfection is approached and diminishes after separation until the planets have moved beyond the relevant limits.

This leads to an extremely important interpretive rule:

Orb determines whether meaningful contact exists; exactitude determines how concentrated that contact is.

An aspect 7° applying is not equivalent in urgency to the same aspect 7 minutes from perfection merely because both satisfy the orb criterion.

9. Partile and Platick Aspects

William Lilly preserves another useful traditional distinction: partile versus platick aspects.

A partile configuration represents very close degree correspondence or exact geometrical perfection in Lilly’s presentation.

A platick aspect operates through the permitted planetary orbs.

Lilly illustrates the principle using Venus and Saturn. Venus at 10° Taurus and Saturn at 18° Virgo are eight degrees away from an exact degree-for-degree trine. Yet because their respective planetary rays permit contact, Lilly considers them in a platick trine.

His explanation explicitly invokes the moieties of their orbs.

The conceptual distinction is useful even when the historical terminology varies between authors:

Partile / exact or near-exact contact
→ concentrated perfection.

Platick / within planetary rays
→ genuine aspectual relationship, but not exact.

For judgment, particularly in horary and electional astrology, this distinction is more useful than simply labeling both configurations “a trine.”

10. Lilly’s Orbs: Why the Numbers Become Complicated

William Lilly’s Christian Astrology is particularly valuable because Lilly openly admits disagreement among earlier authorities.

His table gives one relatively generous set:

But immediately alongside these Lilly records alternative values:

Lilly even remarks that he sometimes uses one set and sometimes the other.

This should prevent us from pretending that traditional astrology always possessed a single universally agreed table.

It did not.

For practical purposes, however, the smaller sequence—

15 / 12 / 7 / 7 / 8 / 9 / 9

—is particularly convenient and historically well attested, and it closely corresponds with the values associated with Al-Biruni and adopted in Dariot’s systematic explanation.

11. The Jupiter–Venus Problem Under Lilly

The difference becomes especially instructive when calculating Jupiter–Venus.

Using the common Al-Biruni/Dariot values:

Jupiter = 9°
Venus = 7°

Effective combined moiety:

(9 + 7) / 2 = 8°

But using Lilly’s larger alternatives:

Jupiter = 12°
Venus = 8°

Effective combined moiety:

(12 + 8) / 2 = 10°

Thus even the statement:

“The traditional orb for Jupiter–Venus is 8°”

requires qualification.

Eight degrees is an excellent value when one explicitly adopts the standard Al-Biruni/Dariot-style table.

But another historically defensible Renaissance table can yield approximately 10°.

This is why serious traditional astrology should always specify the orb convention being employed.

Do not silently mix systems.

12. A Practical Combined-Moiety Table

Using the commonly employed values:

• Sun 15°
• Moon 12°
• Mercury 7°
• Venus 7°
• Mars 8°
• Jupiter 9°
• Saturn 9°

the principal combined aspectual limits are:

This table immediately demonstrates why applying one universal orb to every square, trine, or opposition obscures the traditional model.

A Sun–Jupiter configuration may operate across approximately 12°.

A Mercury–Venus configuration may require approximately 7°.

Both may be trines.

The planets, not merely the aspect geometry, determine the range.

13. Does the Same Orb Apply to Every Major Aspect?

Within the classical moiety model, broadly yes.

The planetary rays determine whether the planets are close enough to interact through one of the recognised configurations.

Thus the same Jupiter–Venus planetary allowance may theoretically govern:

• conjunction
• sextile
• square
• trine
• opposition

What changes is the nature of the geometrical relationship, not necessarily the planets’ capacity to project their rays.

This is radically different from the familiar modern scheme:

• conjunction = 10°
• opposition = 10°
• trine = 8°
• square = 7°
• sextile = 5°

Such tables assign power primarily to the aspect.

The traditional moiety model assigns the extent of influence primarily to the planets.

This does not mean that traditional astrologers considered every aspect identical in strength or nature. Trine, sextile, square, and opposition have different geometrical, elemental, and qualitative meanings.

It means only that orb is not the principal mechanism used to encode those qualitative differences.

14. Orb Is Not Aspect Strength

One of the most common interpretive mistakes is to treat orb as a direct numerical measure of importance.

A planet inside its permitted moiety is not automatically powerful.

Imagine Jupiter applying to Venus from 7°50′.

The aspect may technically be within the standard 8° combined moiety.

But now imagine another Jupiter–Venus aspect only 0°15′ from perfection.

These should not receive identical interpretive weight.

The second is vastly more immediate.

A useful hierarchy is:

Existence of contact → determined partly by orb/moiety

Direction of event → applying versus separating

Immediacy → distance from perfection

Ability to act → essential and accidental condition of the planets

Quality of outcome → planetary nature, reception, dignity, houses and context

Orb is therefore a gateway criterion.

It is not the entire judgment.

15. Applying Aspects Matter More Than Merely Existing Aspects

This becomes especially important in horary and electional astrology.

A separating Venus–Jupiter trine at 7° may still technically remain within their moieties.

But if the question concerns something that must happen in the future, an applying relationship is ordinarily far more important than a wide separating configuration.

Likewise:

Venus applying to Jupiter by 2°

is generally more promising for future perfection than:

Venus separating from Jupiter by 6°

even though both fall within the same 8° theoretical range.

Traditional judgment is temporal.

The astrologer asks not merely:

Are they in aspect?

but:

Are they coming together or moving apart?

That distinction is central to horary and electional practice.

16. Do Angles and Lots Have Planetary Orbs?

Traditional planetary-orb doctrine raises another useful question.

The Ascendant is not a planet.

Neither is the Midheaven.

Nor is the Part of Fortune a luminous celestial body projecting planetary rays.

Consequently, one should be cautious about treating these points as though they possess planetary moieties identical to Venus, Mars, or Jupiter.

Some traditional practitioners therefore evaluate a planet’s contact with an angle according to the planet’s own effective range, often more conservatively than planet-to-planet aspects.

The broader conceptual principle is sound:

A mathematical point should not automatically be granted the same radiating sphere of influence as a planetary body.

This becomes especially important when designing computational systems. Assigning every angle, Lot, Node, asteroid, and hypothetical point an arbitrary 8° orb may be convenient, but it is not a straightforward continuation of medieval planetary-orb doctrine.

17. Outer Planets and the Historical System

Uranus, Neptune, and Pluto obviously do not appear in the medieval tables.

There is therefore no historically authentic “Lilly orb for Pluto” or “Al-Biruni moiety for Neptune.”

Any such number is necessarily modern.

One may choose to incorporate the outer planets into a contemporary traditional practice, but intellectual honesty requires distinguishing:

historical rule

from

modern extension of a historical rule.

A conservative practitioner may use narrow orbs for the outer planets or restrict their importance to very close contacts.

Another may assign them experimental planetary radii.

Both are modern methodological choices.

Neither should be attributed to Dariot, Lilly, or Al-Biruni.

18. The Moon Deserves Special Attention

The Moon’s large 12° traditional radius is not an arbitrary curiosity.

In practical horary and electional astrology, the Moon is extraordinarily important because she describes motion, transmission, unfolding events, and the sequence through which circumstances develop.

Her 6° moiety combines with the moiety of whichever planet she approaches.

Therefore:

Moon–Mercury = 9°30′

Moon–Venus = 9°30′

Moon–Mars = 10°

Moon–Jupiter = 10°30′

Moon–Saturn = 10°30′

This helps explain why lunar applications can remain relevant across distances that might appear excessively wide to a modern astrologer accustomed to a 5° or 6° universal orb.

Yet one should still distinguish between a Moon 10° from perfection and a Moon 1° from perfection.

Both may belong to the same application.

They do not describe the same degree of immediacy.

19. Orbs and Translation of Light

Moieties become particularly useful when evaluating techniques such as translation of light.

Suppose the Moon has separated from Venus and is now applying to Jupiter.

The astrologer must determine whether the Moon was genuinely in contact with Venus and whether she can meaningfully carry that influence onward to Jupiter.

A precise doctrine of planetary ranges prevents translation from becoming an arbitrary statement whenever three planets happen to lie somewhere near one another.

The question becomes:

1. Was the Moon within legitimate contact with the first planet?
2. Has she separated from it?
3. Is she now applying to the second?
4. Is that second application within effective planetary range?
5. Will perfection occur before sign change, station, prohibition, or another interfering condition?

Orb therefore participates in a larger chain of judgment.

It cannot replace that chain.

20. Orbs in Electional Astrology

Electional astrology benefits enormously from using moieties properly.

When selecting a chart, the astrologer should not merely search for aesthetically pleasing aspect lines.

For example:

Venus applying trine Jupiter by 7°45′

may legitimately fall within their traditional 8° combined moiety.

That is meaningful.

But if another election becomes available with:

Venus applying trine Jupiter by 1°20′

while preserving comparable dignity, angularity, lunar condition, and house relevance, the second election ordinarily gives a much tighter perfection.

Nevertheless, closeness must not be worshipped blindly.

A 0°20′ Venus–Jupiter trine in which:

• Venus is combust,
• Jupiter is cadent,
• the Moon is severely afflicted,
• the Ascendant ruler is debilitated,

may be inferior to a 3° Venus–Jupiter application embedded in a structurally powerful chart.

Traditional electional astrology is hierarchical.

Orb is one condition among many.

21. A Recommended Method for Practical Work

For astrologers seeking a coherent historically grounded system, the following procedure works exceptionally well.

Step 1 — Choose one orb table

For general medieval/Renaissance work, a strong default is:

Do not casually switch between this set and Lilly’s larger values chart by chart merely to preserve a desired aspect.

Consistency is methodologically preferable.

Step 2 — Calculate each planet’s moiety

Divide the planetary value by two.

Example:

Jupiter = 9° → 4°30′
Venus = 7° → 3°30′

Step 3 — Add the two moieties

Jupiter + Venus:

4°30′ + 3°30′ = 8°

That becomes the practical maximum distance from exact aspect.

Step 4 — Determine application or separation

Do not stop after detecting an aspect.

Determine which planet is faster and whether exactitude lies ahead or behind.

Step 5 — Measure distance from perfection

An aspect at the edge of its moiety is much less immediate than one approaching exactitude.

Think in gradients rather than binary switches.

Step 6 — Examine reception and planetary condition

Ask whether the planets actually possess the ability and willingness, symbolically speaking, to produce the promised effect.

Consider:

• domicile
• exaltation
• triplicity
• terms
• face
• detriment and fall
• reception
• retrogradation
• combustion
• planetary speed
• angularity
• house placement
• sect
• benefic or malefic condition

An exact aspect between incapable significators can describe a very different result from a wider aspect between powerful and mutually receptive planets.

Step 7 — Give the Moon separate attention

Especially in horary and electional charts, examine:

• her current application,
• previous separation,
• next perfection,
• sign boundary,
• condition of her dispositor,
• impediments before perfection.

Her relatively large traditional orb makes proper moiety calculation especially useful.

22. A Practical Strength Model

For actual interpretation, it is useful to separate contact from strength.

A reasonable qualitative model is:

Outside combined moiety

No strong degree-based aspectual contact.

Just inside combined moiety

Weak or emerging contact.

Approximately middle of permitted range

Established aspectual connection.

Within roughly 3°

Strong and immediate.

Within roughly 1°

Highly concentrated.

Exact or nearly exact

Perfection; maximum immediacy.

These categories should not be converted into rigid universal numerical laws. They are interpretive aids.

A 4° application of the Moon can unfold rapidly.

A 4° application of Saturn may represent a much longer temporal process.

Orb gives spatial relationship.

Planetary speed gives temporal meaning.

23. Why Fixed Aspect Orbs Are Attractive — and What They Lose

Modern fixed-orb systems are popular for good reason.

They are simple.

A software program can say:

Trine = 8°

and immediately determine every trine in the chart.

But simplification comes at a conceptual cost.

Compare:

Sun trine Moon at 10°
Mercury trine Venus at 10°

A universal 8° system rejects both.

The traditional moiety system treats them differently.

Sun–Moon:

13°30′ maximum

Therefore the 10° trine is within their traditional planetary reach.

Mercury–Venus:

7° maximum

Therefore the 10° configuration lies outside their combined moieties.

This is not an accidental numerical difference.

It expresses a cosmological judgment:

The luminaries project more extensive influence than Mercury and Venus.

The traditional system therefore embeds planetary hierarchy directly into the mathematics of aspect formation.

24. The Most Important Historical Caution

One should resist two opposite errors.

The first is modern simplification:

“Every trine gets 8°, every sextile gets 5°.”

The second is pseudo-traditional dogmatism:

“Every historical astrologer used exactly the Dariot moiety formula.”

Neither statement is historically satisfactory.

Al-Biruni’s discussion demonstrates the coexistence of several approaches to limits of influence. Dariot offers a particularly clear and influential formulation of the combined-moiety system. Lilly employs the concept of moieties explicitly but simultaneously records disagreement over the planetary values themselves.

The better conclusion is:

Traditional astrology possessed a planetary theory of orbs, within which several computational conventions existed. The combined-moiety method became one of the most coherent and practically useful expressions of that theory.

25. Recommended Standard for Contemporary Traditional Practice

For a practitioner who wants one consistent system rather than an endless mixture of authorities, I recommend the following baseline:

Planetary orb radii

Sun — 15°
Moon — 12°
Mercury — 7°
Venus — 7°
Mars — 8°
Jupiter — 9°
Saturn — 9°

Aspect allowance

Use:

(Orb of Planet A + Orb of Planet B) / 2

Thus:

Jupiter–Venus = 8°

Moon–Jupiter = 10°30′

Sun–Saturn = 12°

Mercury–Venus = 7°

Do not then apply an additional “trine orb” or “square orb” on top of this.

The aspect geometry tells you what kind of relationship exists.

The planetary moieties tell you whether the planets are close enough for that relationship to become operational.

26. When to Depart From This Standard

A different historical table may be justified when deliberately reconstructing a particular astrologer’s practice.

For example, when working explicitly within Lilly’s own framework, one may experiment with his broader figures:

• Sun 17°
• Moon 12°30′
• Jupiter 12°
• Saturn 10°
• Venus 8°
• Mars 7°30′
• Mercury 7°

But this should be documented as a methodological choice.

Likewise, astrologers conducting historical research may compare:

Al-Biruni-style limits

against

Dariot’s moiety implementation

against

Lilly’s broader alternatives

to determine whether specific judgments materially change.

What should be avoided is unconscious hybridization:

using 17° for the Sun because it preserves one desirable aspect, 9° for Jupiter because it eliminates another, and a modern 5° sextile orb somewhere else.

A traditional method should be coherent enough that another astrologer can reproduce the judgment.

27. Final Principles

The entire doctrine may be condensed into several principles.

First:
Traditional planetary orbs belong primarily to planets rather than to aspect types.

Second:
A moiety is the half-measure used to determine how the influence of one planet meets that of another.

Third:
Under the widely used Dariot-style method:

Aspect allowance = moiety of Planet A + moiety of Planet B

or:

Aspect allowance = (Orb A + Orb B) / 2

Fourth:
A Jupiter–Venus aspect therefore does not simply receive some universal “trine orb.” Using the standard 9° Jupiter and 7° Venus values, its combined moiety is 8°.

Fifth:
Change either planet and the effective range changes.

Sixth:
Change the historical orb table and the range may change again. Lilly himself preserves competing values.

Seventh:
Being within orb establishes contact; it does not make every aspect equally powerful. Exactness, application, reception, dignity, house position, planetary speed, and freedom from impediment remain essential.

Eighth:
For horary and electional astrology, an applying aspect approaching perfection usually deserves much greater attention than a similarly wide separating aspect.

Ninth:
Do not assign medieval authority to arbitrary orbs for Uranus, Neptune, Pluto, asteroids, Nodes, Lots, or angles. Any such extension should be identified as modern.

Tenth:
Consistency matters more than pretending that one historical table is universally correct.

Conclusion

Traditional orb doctrine reveals a fundamentally different conception of planetary aspects.

An aspect is not merely a geometrical angle surrounded by an arbitrary tolerance.

It is the meeting of planetary rays.

The geometry describes the form of the relationship.

The planets describe its actors.

Their condition describes their capacity.

Their reception describes their relationship.

Application and separation describe its direction through time.

And their orbs determine the spatial range within which their influence can effectively meet.

This is why Jupiter trine Venus at 7°30′ cannot be judged simply by asking whether “a trine allows eight degrees.”

The correct traditional question is:

How far do Jupiter and Venus respectively extend their rays, are those rays already meeting, and are the planets applying toward or separating from perfection?

Using the standard Al-Biruni/Dariot values, Jupiter contributes a 4°30′ moiety and Venus contributes 3°30′. Together they produce an 8° field of effective aspectual contact.

Replace Jupiter with the Moon and the field expands.

Replace the Moon with Mercury and it contracts.

That relational principle—not a single fixed orb attached mechanically to the aspect—is the heart of the traditional doctrine of orbs and moieties.

Primary and Historical References

Al-Biruni. The Book of Instruction in the Elements of the Art of Astrology (Kitāb al-Tafhīm), 11th century.

Claude Dariot. L’Introduction au jugement des astres / A Briefe and Most Easie Introduction to the Astrologicall Judgement of the Starres, 16th century.

William Lilly. Christian Astrology, 1647, particularly the discussion of partile and platick aspects and the table of planetary orbs around pp. 106–107 in standard reproductions. Lilly explicitly describes platick aspects through the moieties of the participating planets and records both larger and smaller orb values.

For a detailed modern historical synthesis of the development and use of these doctrines, Deborah Houlding’s study of the classical origin and traditional use of aspects provides a useful comparison of Al-Biruni, Dariot, Lilly, and earlier sources.