Quintile aspect: the 72° angle missing from your reports

360° divided by five gives 72°, the central angle of the regular pentagon. The quintile falls neither on a whole number of signs nor on half a sign: Lilly describes it as “two signs twelve degrees.” So it cannot arise from the division of the zodiac into twelve, which is where all of Ptolemy's aspects come from.

Its family includes other angles: the biquintile (144°), two fifths of the circle, and, for some authors, the semi-quintile or decile (36°) and the sesquiquintile or tredecile (108°).

Johannes Kepler (1571-1630) wanted to reform astrology by grounding it in geometry and musical harmony rather than in the signs. According to David Plant's study of him on Skyscript, he added the quintile, the biquintile and the sesquiquadrate to Ptolemy's aspects, and associated the quintile with the major third, in the ratio 4 to 5. He rejected a division by seven, however: the seven-sided polygon cannot be constructed with ruler and compass, and Kepler would not accept it as the basis of an aspect.

The Urania Trust, which traces his career, reports that he claimed to find proof of these new aspects in their effects on the weather. David Plant adds that he also relied on the analysis of his collection of some 800 birth charts, and that he held this geometric imprint of the sky to be more important than the signs and houses.

William Lilly, in Christian Astrology (1647), first meets it in the ephemerides: the symbol Q marks a quintile there, for instance between the Sun and Saturn. On page 32 of book I, he notes that we seldom use more than the conjunction, sextile, square, trine and opposition, lists the quintile among Kepler's additions, and says he mentions it only so the reader may understand it.

In book III, though, he puts it to use in the directions of an English merchant's nativity: the Ascendant directed to the quintile of Mercury foretells accounts set in order and profit from Mercurial people and things. And he concludes that semi-quintiles, quintiles, sesquiquintiles and biquintiles are, in judgment, of the nature of the sextile and trine, but do not operate altogether so strongly.

Since you will not find it in your report, you can estimate a quintile by hand. Add two signs and twelve degrees to a body's position, the measure Lilly gives: from 6°37' Scorpio, two signs take you to 6°37' Capricorn, and twelve more degrees to 18°37' Capricorn. A body placed near that point is in quintile to the first. Do the same in the other direction, subtracting 72°.

For the biquintile, the angle is double, 144°: four signs and twenty-four degrees. Lilly uses it in his directions too, where the biquintile of Mars to Saturn foretells that an aged friend of the native will uncover a servant's fraud. These calculations remain yours: no AstralPro report includes them.

In modern astrology, the quintile is often associated with creativity, talent and the expression of a personal intention. The Skyscript glossary sums it up this way, tying this meaning to the division of the circle by five. It is neither a tension to resolve nor a passive ease, but a capacity to combine two functions in an original way, one that needs to be cultivated.

In this reading, Mercury quintile Neptune would link thought and imagination: a knack for putting words to what escapes reasoning, a potential to explore rather than a gift already in hand.

AstralPro works with a single table of nine aspects: the five majors (conjunction, opposition, trine, square, sextile) and four minors (quincunx, sesquiquadrate, semi-square, semi-sextile). The quintile is not part of it, nor is any aspect in its family. It therefore has no orb, and an aspect without an orb does not exist for the engine: it is neither detected, nor displayed, nor discussed.

In practice, you will not find it in the complete natal aspect grid, on the wheel, in the chapters, or in the aspect tables of the Book, the solar return or the compatibility report, which stick to the five majors. The legend of the aspect table does not mention it either. This choice limits the grid to the aspects the chapters know how to read, from 0° to 180°, on the division of the circle by twelve and by eight.

If you come across a quintile elsewhere, in software or with an astrologer, it does not contradict your report: it is a different aspect table. Your report says nothing about a quintile, neither to confirm it nor to rule it out.

Camille Morel, AstralPro's sample chart (fictional data), would nonetheless have several, and very tight ones. From the positions in her table, Mercury (6°37' Scorpio) and Neptune (18°56' Capricorn) are 72°19' apart; Venus (6°30' Scorpio) and Neptune, 72°26'. Mercury and Venus are also 72°33' and 72°40' from Uranus (19°10' Capricorn). That makes four gaps within a degree of the exact quintile. Since Mercury and Venus are conjunct, and so are Uranus and Neptune, these four gaps describe a single pattern: two pairs of planets a fifth of a circle apart.

An astrologer who uses the quintile would spot them at once, all the more since Mercury and Venus are conjunct at 0°07' and Uranus and Neptune at 0°15'. In Camille's report, none of this appears: her grid of 40 aspects links Mercury and Venus neither to Uranus nor to Neptune. This is not an omission; it is the direct consequence of AstralPro's table.