Rectifying Kepler’s Birth Chart

Astro.com gives Johann Kepler’s birth data as 27 December 1571 Jul.Cal. (6 Jan 1572 greg.) at 14:37 LMT (= 2:37 PM ) in Weil der Stadt, Germany, 48n45, 8e52, and cites Kepler’s autobiography as the source. This chart has an Ascendant of 24 Gemini 25′ and is apparently Kepler’s rectification of his birth chart based on his accepted birth time of 2:30 pm LAT.

According to Kepler’s own writings, he became deeply interested in astrology during the period around 1590, having studied it at the university. Kepler began to cast charts, including his own, to study their symbolism and make predictions. For example, in 1595 Kepler cast the birth chart of Christoph Ortolph, a former fellow student at Tübingen, and in a letter warned him of the possibility of his death in two years time. Ortolph did not take Kepler seriously and responded in jest. However, two years later Kepler’s old friend died of the plague. In his notes Kepler wrote: ‘He died in the year 1597 from the plague, two years after I predicted it to him’. Unfortunately, I have been unable to locate a copy of Kepler’s birth chart for his friend Christoph Ortolph.

In working with his own chart, it appears that Kepler understood his birth time to be about 2:30 PM, probably from family sources. Realizing that the 2:30 PM might be an approximate time, he apparently sought to recifty the chart, or at least to verify the time he believed he was born. To do so, he experimented with two other charts cast for 1 PM and for 1:30 PM, both of which he noted in Latin “fuit H.2:30” or “fuit hora 2 1/2” meaning that “it was [originally] Hour 2:30” — his accepted birth time.

After experimenting with these three charts and trying to verify key events of his life with primary directions (Regiomontanus circle of position method), Kepler concluded that the 2:30 PM time was the most accurate. However, he could not identify an astrological reason for a severe bout of acute fever in 1591. In search of an explanation for the failure of astrology to explain his fever, he wrote to the noted astrologer-physician Helisaeus Röslin (1544-1616) asking why he could not find the cause, using primary directions, for the fact that during the Bacchanals of 1591 [around mid-March when he was 19.2 years old] he endured an intense, sharp, and burning fever.

This is Kepler’s chart from Astro.com. It is calculated with Placidus houses (Kepler used Regiomontanus) and Kepler’s time of 2:30 PM LAT has been converted to the equivalent 2:37 PM LMT to generate an Asc of 24 Gem 25′.

Röslin graciously replied on 17 October 1592 with a brief delineation of Kepler’s birth chart and included an explanation of the primary direction involved in the fever of March 1591. He began with a general comment: “The nativity seems to be rather violent (violenta), since one luminary, the Sun, is in a violent sign, and the other, the Moon, is with a violent fixed star, the eye of Taurus. And one of the malefics, Mars, damages the Sun with a square aspect. Likewise Mercury, the lord of the Horoscope [Ascendant], is in a violent sign and afflicted by Mars.”

The Sun and the Asc-ruler Mercury both occupy Capricorn, which is a “bestial” sign, sometimes considered violent. In the Indian tradition Capricorn is a sea-monster. For example, in Pingree’s translation of the Yavanajataka, he writes: “The first Hora in Capricorn is a man with jagged teeth who is hideous, and fierce, armed with a club like Death at Doomsday. He breaks the peace, this wearer of a deer-skin.” Similarly, the first decan of Capricorn, where the Asc-ruler Mercury resides, is described in these words: “The first Decan in Capricorn is the color of collyrium. His teeth are as terrible as a crocodile’s. He is armed with a staff, and his actions are like those of Time and Death. He stands in the middle of a cemetery with an armor of heavy hair and a strong body.”

Because Röslin chose to describe Kepler’s nativity with the Latin adjective “violenta,” I looked up the meaning of the word “violentus” in Latin. While it often literally means violent, it can also be used to mean powerful, forceful, overbearing, impetuuous, fierce, aggressive, intense, vehement, overwhelming, or exceeding normal bounds or natural limits. In addition, like many Latin adjectives, “violentus” can carry both negative and neutral connotations depending on context — sometimes simply meaning “powerful” or “forceful” without necessarily implying wrongdoing. It may be that Röslin was impressed by Kepler’s chart and realized that the native was a forceful person who stood out from the crowd.

Regarding the acute fever in March of 1591, Röslin notes that the dexter square of natal Mars (which occupies 8 Libra 16′) lies in the natal 1st house at 8 Cancer 16′ about 14 degrees from the Ascendant and, given an approximate birth time of 2:30 PM LAT, would reach the Ascendant by primary motion in his late teen around the time he suffered the fever. Mars is a “hot” planet associated with acute illness and high fevers. The square of Mars, with natal Mars ruling the 6th house of illness, conjunct the natal Asc by primary direction could certainly signify an acute febrile illness. Röslin also writes to Kepler that primary directions don’t necessarily manifest exactly on time, so that even if this direction of the square of Mars to the Asc perfected before he turned 19 years old, its effects could still show up at age 19.2, depending on other astrological factors active at the time.

In In Röslin’s own words (italics mine): “I have learned this much in astrology, that one can’t tie these things to years, let alone days, especially when we may not be sure of the minute of birth. And if the Lord [referring to Kepler who contacted him] were reckoned to have been born even 20 minutes before, [with] 19 degrees 30 minutes rising, and the Horoscope [Ascendant] will meet Mars’s square aspect in the 21st year of life. This meeting could certainly cause a burning fever of this nature. But I shall reckon that the Lord was born at the hour I have in the present chart [2:30 PM LAT]; still, it could be that the square of Mars delays the effect because of another direction, that of the Sun, to conjunct the South Node, which happens only in the 23rd year of life.”

The astrologers of the 1590s would have been using Regiomontanus Houses and the Regiomontanus method of primary directions. I don’t know which timing key Röslin used, but assuming he followed Ptolemy’s rule that 1 degree of Right Ascenstion across the MC = 1 year of life, Röslin’s suggestion that the dexter square of Mars on the eastern horizon by primary motion would yield the following birth chart for Johann Kepler (using the zodiacal position of Mars and not accounting for the latitude of Mars). Röslin points out, however, that the directed Lunar South Node will conjoin the 8th house Sun a couple of years after the directed square of Mars conjoins the Asc, so that the combined influence of the two directions may affect the exact timing of either of them. Thus, a rectified time closer to 2:30 PM LAT is still possible. In Röslin’s own words: “But the method is not that certain that one can pin it to a certain time, as many particulars will take effect and interrupt heaven’s universal laws, so that their effect is either to speed up or delay.”

Accounting for the dexter square of natal Mars rising to the horizon at age 19.2, this rectified chart has a birth time of 2:22 PM LMT and an Asc of 20 Gemini 39′. Clearly, one cannot rectify a chart based on a single event, but this chart at least addresses Kepler’s concern about finding an astrological indication of a severe bout of high fever around age 19 if he were indeed born around 2:30 PM LAT.