Karine Dilanian – Meteorological astrology by Johannes Kepler and Georg Kraft’s prediction for ice drift on the Neva River in 1732

Institute for the Study of Astronomy and Cosmology in History, Philosophy and Culture.

Moscow, Russia

Email: [email protected]


In 1732 Russian academic, Georg Wolfgang Kraft published an article, in which he promised his readers to reveal his method of predicting the ice drift on the Neva River based on planetary aspects. The publication also focused on supporting the validity of astrology, and for this purpose, he suggested a special method for prognostication, based on Kepler’s understanding of the power of aspects that are geometrical ratios between planets.  Kraft claimed that he expected support from the glorious Kepler. This study examines Kraft’s method of meteorological prognostication and his statements concerning astrological models of planetary aspects connected with musical harmony and geometrical ratios and compares them to Kepler’s principles presented in his works: Harmonices Mundi and Concerning the More Certain Fundamentals of Astrology, as well as Kraft’s reception, examination and application of Kepler’s principals in his own research.  The methodology of this survey is based on a comparative approach to studying historical and literature documents that are archival sources and philosophical literary work in order to investigate general concepts, analyse their interrelations, find similarities and differences as well as to establish dialogic relations with other texts and contexts. The study demonstrates a strong connection of Kraft’s article to Kepler’s treatises as well as his methodology of astrological meteorology based on Kepler’s theory and method. Finally, the study argues that Kraft builds his experimental study on Kepler’s methods, not only repeating, but also testing and validating them.

Key words: Georg Kraft; Johannes Kepler; Harmonices Mundi; meteorological astrology; planetary aspects;


On July 20 1732, the Primechaniya na Sankt-Peterburgskiye Vedomosti magazine published an article ‘About the St. Petersburg Calendar of This 1732’ (1732, 257-262). The author of the article says that as the storyteller of this calendar he undertakes an attempt to make a prediction and promises his readers to answer a question in public: ‘When will the ice on the Neva River start to drift this year.’ The author declares that he will explain how he made this prediction, with two purposes: first, to reveal it by means of heavenly aspects, and secondly for some entertainment. And though the second purpose can seem frivolous, it gives him a chance to pass on a message about astrology in general. In addition, he expects support from ‘glorious Kepler’(1732, 257). This paper will explore the application of Kepler’s meteorological astrology in 1732.


This study examines the author’s method of meteorological prognostication and his statements concerning astrological models of planetary aspects connected with musical harmony and geometrical ratios and compares them to Kepler’s principles presented in his works: Harmonices Mundi and On the More Certain Fundamentals of Astrology. The aim of the study is to find interrelations of philosophical concepts of the two authors, allocate the basic concepts by which they operate in formulation of their ideas and bridge their theories with the previous philosophical approach and critical views. The study aims to prove that the author of the article used Kepler’s theory and method of the meteorological prognosis, applied them to his own work and tested them in his experimental research.

It was Michail Bakhtin, who argued that dialogue, comparison, collation are the most general principles of culture and life and pointed out that the text lived only adjoining to other text or context. Bakhtin specified that only in a point of contact of two texts, light flashes the road both forwards and backwards, thus, attaching this text to a dialogue (Bakhtin 1979, 364). The methodology of this survey is based on a comparative approach to studying historical and literature documents that are archival sources and philosophical literary work in order to investigate general concepts, analyse their interrelations, and find similarities and / or differences as well as to establish dialogic relations with other texts and contexts.

The author of the calendar

Although the article was anonymous, Pyotr Pekarsky (1828-1872) in his History of the Imperial Academy of Sciences in St. Petersburg claims that the author was the academician of the Russian Academy of Sciences, physicist and mathematician Georg Wolfgang Kraft (1701-1754), from Wurttemberg (1870, 465).  In the Saint Petersburg Academy of Sciences Kraft worked under the leadership of the astronomer Joseph-Nicolas De L’Isle (1688-1768), a loyal follower of Johannes Kepler and Isaac Newton. Nina Nevskaya states that De L’Isle had compiled a list of 405 academic books, which he recommended to every fellow astronomer of the observatory and used as part of the curriculum at the observatory in Saint Petersburg; this list contained about twenty titles by Johannes Kepler (1994, 12). Nevskaya mentions that while being an astronomer, De l’Isle also carried the title ‘court astrologer’, which he passed to Kraft later (1994b, 21). Kraft’s colleague Jacob von Stäehlin (1709-1785) recollects that the Russian empress Anna Ioannovna (1693-1740) passionately believed in astrological predictions and she often addressed the Academy for answers to different questions and tasks. Stäehlin points out that ‘this business always concerned professor Kraft, who solved surprising problems like the anonymous horoscope of the unfortunate Prince Ioann, as well as giving meteorological prognostications’ (Pekarsky 1870,461). Pekarsky writes that Kraft’s duty since 1729 until 1735 was to do meteorological observations along with calculations of calendars (1870, 461).

The content and the structure of Kraft’s article

Kraft’s paper is a small text of approximately 1500 words, which consists of several, logically built, passages. In a short introduction to the article heestablishes a problem statement: first, he promises to open his methodology of making weather prognosis that is prediction of the ice drift on the Neva River, which he made with the help of heavenly aspects and second, to introduce brief general reasoning on astrology in a form of entertainment (1732, 257). He then turns to the description of the rather deplorable condition and poor state of astrology in his time. Kraft complains that philosophers severely reject it and never defend astrology. However, he claims ‘together with glorious Kepler’ that it is unreasonable to sweep aside all science and explains the cause as to why philosophers reject astrology: he acknowledges that astrological predictions have no fundamentals and they seldom come true. He critically remarks that they ‘far extend from the human birth, wellbeing and death’ and states that few astronomers know astrology. Finally, he points out that astrologers try to predict remote events (1732, 258). He speculates that astrological prognostications rarely come true because those who foretell events try to predict particulars concerning human lives such as illnesses, marriages and temporary welfare, while true astrology sweeps aside it as false dreams. Those with the astronomical eye who are free from prejudice can see that the true science considers general, but not particular things (1732, 258).

Kraft suggests a study of several cases as examples of his daily observations. He takes 22 October 1731 with the aspect of opposition of the two planets, Jupiter and Saturn, saying that opposition is considered ‘the cruelest aspect’ (1732, 259). Severe motion of air, frost and icy cold marked this very day, while the previous day was quiet and soft. In addition, these weather conditions stayed for a few days, due to the duration of the slow movements of these planets. The other example is a study of planetary positions on 25 January 1732, when Jupiter changed its direction, became retrograde, and thus repeated his previous cruel aspect, which brought the same weather conditions as in the earlier mentioned case. However, in the case of a different aspect, that was a trine aspect of Saturn and Sun, which occurred on 23 October 1729, severe flood took place. It happened because of the strong wind on that day. Kraft suggests an objection that his opponents may put forward saying that such weather should stay over the entire territory of Europe, but it was not the case. For instance, the same severe aspect that brings storm, flood and snow to Saint Petersburg will bring heat, dry or rain in Spain or Italy  (1732, 259).

In the next passage, Kraft bridges planetary aspects that produce weather changes to the changes in the human soul: cruel aspects that occur during a birth of a baby provoke manifestations of cruelty. Moreover, if this baby becomes a soldier in future then it is very possible that he will be brave and courageous, but if he becomes a scholar, then he will be cruel in disputations, as well as in relations with his colleagues, but if he becomes a theologian then he will be jealous to the related subjects and the like. Kraft draws a conclusion that planetary aspects are the most important factors of astrological impact; therefore, it is possible to throw out all other astrological rules, such as a concept of twelve astrological houses, or a theory, concerning special characteristics of planets in different astrological signs, and other numerous trifles as groundless nonsense (1732, 260). As for the astral force that enters earthly bodies and acts inside them, Kraft argues that he never made any assertions concerning this topic; therefore, there is nothing to dispute. He seeks the cause of all effects in a highest being and puts ‘the indisputable truth up for discussion: what is the reason for our soul getting excited listening of music?’ (1732, 260). Kraft answers this question stating, that our senses rise not from the changes and movements of air, but those movements that have an appropriate order and a proportion. In one word, because the soul in its motion has something geometrical, which exists in her being. He explains the pleasantness of listening to the octave in a simple geometrical proportion, such as relation of 2 to 1. The same takes place in the case of the aspects: when, for example, two planets are in the aspect of opposition to each other, then the distance between them is half of a circle and relate to the whole circle as a half to the whole, or 2 to 1. The trine aspect is a sort of musical fifth, while quartile aspect is a quadrangular quart and so on (1732, 261).

Kraft speculates that during a birth of a baby, astrological planetary aspects compound a melody that sounds like a musical orchestra, which enters the world with light. Those harmonious voices that a newborn hears at birth will sound in his ears during all his life; therefore, the aspects are the only basis for astrological predictions. He harkens to the ‘ancient times’ when aspects ‘with reason’ were accepted as the main bases for astrological prognostication. Moreover, astrological aspects have only some, but not complete application; therefore, they allow the free flow of things (1732, 261). After these statements, Kraft turns to explaining his method of astrological prognostication using his prediction for the beginning of the ice drift on the Neva Riva. He points out that he studied his previous notes on the ice drift and analysed the aspects, which accompanied this process. He also marked the period of time, during which this event previously occurred and selected a number of aspects that may influence and can be a trigger to the ice drift. He then listed selected aspects and presented his judgment: he had chosen opposition of Mars to Venus, which he considered stronger then the trine between Jupiter and Venus and, therefore, he pointed to the 9 April, the day of the exact aspect between Mars and Venus. However, the ice started its drift on 5 April, when the previous trine aspect between Jupiter and Venus took place. Therefore, it was this very aspect, which is the reason for the meteorological event under study. Kraft concluded that as he opened his method of astrological prognosis for meteorological events to the public, from then on there was no need to make predictions on such matters, because everyone could make them by themselves (1732, 262).

Interrelation of Kraft’s text with the other texts and philosophical concepts: Kepler, Pico and Ptolemy

The astro-meteorological calendar genre of Kraft’s article and his appeal to ‘glorious Kepler’ connects this text to Kepler’s treatise On the More Certain Fundamentals of Astrology, published in Prague in 1601 (1979). In this work, Kepler makes meteorological prognosis for the year 1602 for the geographical coordinates of Prague based on astrological principals. However, before presenting his month-by month prognosis, he discusses ‘the more certain fundamentals of astrology’, from physical and geometrical standpoints (1979, 89).  One of the goals that Kepler establishes in this treatise is to attract attention of general public to the ‘astrological matters’, whereas ‘cultivating the curiosity of the crowd’ he seeks to reach ‘the learned lying hidden here and thereby any other means than a public one’ (1979, 90).  Kraft in his article follows Kepler’s goals in his aspiration to enlighten the public and introduces his prognosis as a ‘brief general reasoning on astrology in a form of entertainment’, however, keeping in mind philosophers, to whom he addresses his arguments (1732, 257). Kraft’s aim is to rehabilitate astrology, which ‘had never been in such contempt as nowadays’. He lists the main objections to astrology that avert philosophers from it. The charges that astrological predictions have no fundamentalsare such: they seldom come true, they remote far from human life, astrologers try to predict particulars instead of general trends and so on  (1732, 258).

These statements immediately place his article in a core of a dispute into which Kepler was engaged throughout all his scientific life with the avid critic of astrology – Giovanni Pico della Mirandola (1463-1494). Kepler refers to Pico in several works constantly going into open debate and in his Harmonices Mundu as well (1997, 349). In the More Certain Fundamentals of Astrology Kepler calls Pico ‘the enemy of astrology’ (1979, thesis 49, 99). Robert Westman speculated that Kepler was aware of Pico’s critique of the divinatory astrology from the early period of his studies in 1596 and ‘even twenty years later, in the Harmonics, Kepler still believed that Pico’s Disputations was the major text with which he had to engage to establish the legitimacy of any kind of astrology’ (2011, 321).

Though Pico’s name did not appear in Kraft’s article, his complaints of the rather low state of astrology and astrologers, his challenging of astrological fundamentals, questioning of value of astrological predictions with all evidence repeat the main accusations expressed by Pico in his Disputations against Divinatory Astrology. Pico wrote this in-depth anti-astrological treatise in 1493–1494, which appeared in 1496, after the author’s death. There, Pico analysed and categorically denied all astrological theoretical and practical statements as well as he sought to disprove any value of astrology (Akopyan, 2018, 45). His negations touched main astrological postulates such as number and order of planetary spheres, number and quality of the zodiacal signs as well as their divisions into different parts. He denied Aristotelian qualities attributed to the planets, rejected the impact of Jupiter-Saturn conjunctions on earthly affairs and the Great Year, he criticized astrological house systems and astrological aspects. Pico pointed out to astrological controversies and contradictions, denied determination of one’s destiny by planets, and considered only physical impact from the influence of the stars (Akopyan, 2018, 46, 67-80).

However, Kepler in his Harmonices Mundi claimed that he effectively rebutted and refuted philosophical arguments of Count Giovanni Pico Mirandola, which he opposed to astrology (1997, 349). Nevertheless, Kepler tried to find some rational provisions in Pico’s criticism. He states (Kepler, 1997, 361):

At the same time there was passing before my eyes the comparison between the aspects and the musical consonances, which was handed down by Ptolemy, expounded by Cardano and too rashly indeed cast off by Mirandola. By this analogy I was very greatly assisted in my hunt for the causes. For many objections, which Mirandola made to the aspects I saw, could also be made to the harmonizing of two voices.  

As Rabin puts it, citing Kepler’s Tertius Interveniens, he finally extracted it out ‘of an evil-smelling dung heap not also a good granule from a busy hen, a peach, or gold nugget’ (Kepler 1941, 161). She argued that Kepler’s ‘gold nugget’ was the concept of aspects: the angles at which the light rays of two planets appear to strike the earth (1997, 754). Kepler defined planetary aspects as a configuration for the angle between two rays (1997, 326):

. . . each descending from its planet, the angle at which two rays meet here at the Earth, which is deemed to be a point, or which comes to the same thing, it is used for the arc of the same circle, drawn on the zodiac, the arc, which is the measure of the said angle; or the arc, which the two planets seem to mark out by the interpositions of their bodies and, so to speak, cut off for us, dwellers on Earth.


The proof of the validity, efficacy and active impact of the aspects on the earthly conditions became weather prognostications. Here Kepler follows tradition founded by Claudius Ptolemy (100-170) in his treatise Tetrabiblos, where he established rational basis for the astrological prognostication, using combinations of planets, fixed stars and planetary aspects for predicting meteorological phenomena  (2001, 197). Ptolemy appealed to the natural experience of those, who ‘have by necessity become used to making observations’ like farmers, shepherds or sailors, know the special signs of meteorological phenomena that ‘arise periodically by reason of the aspects of the moon and fixed stars to the sun’ (2001, 9). He suggests considering human individual temperament, based on the natural observation of the movements of all the stars, the sun, and the moon that are the ambient at the time of his birth. These entities ‘predict occasional events by use of the fact that such and such an ambient is attuned to such and such a temperament and is favorable to prosperity, while another is not so attuned and conduces to injury’ (Ptolemy 2001, 13).


In his reasoning Kepler uses Ptolemy’s arguments while explains connection between astrological aspects, or geometrical ratios and the celestial harmonies: ‘certain geometric ratios produces beauty in the harmonies’ (1979, thesis 43, 98). He appeals, like Ptolemy, to the experience of a peasant, who does not aware of the geometric ratios; however, when external harmony flow into his ears and reaches his mind, it cheers a man (1979, thesis 43, 98).


Kraft follows the same track stating that planetary aspects were accepted as an active force ‘even in ancient times’, and though he does not mention Ptolemy, however, evidently he keeps his approach in mind due to the application of this concept: planetary aspects are the only natural basis for astrological prediction (1732, 261). He points out that the changes in our senses arise from the movements that have an order and a proportion that is geometry, which exists in the soul’s being, thus, bridging Ptolemy’s and Kepler’s approaches (1732, 261).

Musical harmony, human soul and astrology

The section of Kraft’s text, in which he speculates on the planetary aspects that produce the changes in the human soul, is based mainly on the 40 and 43 thesis of Kepler’s Fundamentals. There Kepler defines the faculty of the soul, which adds force to the aspects and is not located in the stars themselves as a condition, flowing from the accidental arrangement of pairs of stars with the earth. He adds that ‘every animate faculty is the image of God the Geometer in creation, and He is inspired to His task by this celestial geometry of aspects, or harmony’ (1979, thesis 40, 97). Kraft completely assimilates this idea, presenting it in a manner of a debate: he writes that never stated that there is some astral force, which enters earthly bodies and acts inside them, Kraft argues that he never made any assertions concerning this topic; therefore, there is no subject for a polemic. He seeks the cause of all effects in a highest being (the God the Geometer in Kepler’s terms), and puts forth ‘the indisputable truth for discussion: what is the reason because of which our soul is excited from listening of music?’(1732, 260). He answers this question, following Kepler’s concept of God’s ordaining aspects from the musical harmony: ‘God the Creator either took the laws for ordaining aspects from the harmonies of music within an octave… or attuned to the ears of man, which are judges of those consonances, to the heavenly aspects.’(Kepler, 1997, 350). Kraft’s answer to the question is such: planetary aspects are produced not by the entering force, but on the contrary, they depend on the ‘far highest power’. As for the soul, speculates Kraft, being in motion, it assimilates a musical harmony, which in turn, has something from Geometry that is its inherent essence (1732, 260). In addition, Kraft discusses the problem of non-determination of one’s destiny and character by the horoscope, stating that astrology can predict general tendencies, but not particulars in human life. Astrology speaks only about certain traits of a character of a newborn, which will have an impact on its manifestations in the future (1732, 261). Kepler expresses this viewpoint in Book IV of his Harmonices, speculating on human behavior, that is ‘architect of fortune’ (1997, 378). He considers that ‘if anyone has adequate conjectures from the shape of heaven at a nativity about qualities of mind, he will make a conjecture which is not absurd about man’s fortune in general; but it will be only a conjecture and nothing else’ (1997, 378).

Methodology of astrological meteorological prediction: Kepler and Kraft

Kepler sought how he could defend his doctrine of aspects, so he studied them following weather phenomena. He began to consider using them carefully as a cause, connecting to the weather condition as an effect. In the Harmonices Mundi Kepler explained that he made observations of the state of the atmosphere due to its calmness or disturbances and linked it to the juxtapositions or configurations of the planets that are planetary aspects. He noticed that the atmosphere disturbances occurred when there were planetary conjunctions or planets configured in aspects, but if it was generally calm in the atmosphere then few or no aspects took place or such aspects took place that quickly completed (1997, 360).  Kepler presented his considerations on planetary configurations connected to weather prognosis in his More Certain Fundamentals of Astrology. The first two chapters of his treatise are devoted to the physical and geometrical theoretical justification of his statements, while the third chapter contains a detailed weather forecast for the year 1602.


Kepler presented his judgment as follows: he recorded a list of planetary aspects for all twelve months of the year and provided his vision of the weather for each month and for definite days in the said month (1979, thesis 52-62, 100-102). Kraft follows Kepler’s treatise even in composition of his article: the first two large passages are devoted to the theoretical statements, while the third part includes his meteorological observations and their analysis in connection to the astrological aspects. Kraft presents his method of meteorological prognostications based on Kepler’s understanding of the power of aspects that are geometrical ratios between planets.  This method rests on constant meteorological observation, collection of astrological data for further research and its analysis. Thus, he studies the case of Jupiter-Saturn exact opposition that took place on 22 October 1731 and points out that during that day there was cruel icy cold, blizzard of sand and snow (1732, 259).

Figure 1. Opposition of Jupiter and Saturn on 22 October 1731.

Kepler in his Harmonices Mundi considers this aspect to be the most influential and strongest of all other, ‘the perfect congruence and a kind of basic principal all other congruence’ (1997, 341).

Figure 2. Opposition configuration. Kepler, Harmonices Mundi, Book IV (Kepler, 1997, 329).

In his observation of the weather and its correspondence to the planetary aspects on 23 October 1729, Kraft notes that Saturn forms a trine aspect to the Sun that produced big flood, which happened from strong wind (1732, 259).

Figure 3. Trine aspect of Sun to Saturn: 23 October 1729.

Kepler considers the trine aspect of less power than opposition that is of the third degree of influence; however, triangle is the pre-eminent of all aspects, formed by division of the circle into tree (1997, 342-343).

Figure 4. Triangle configuration. Kepler, Harmonices Mundi, Book IV  (Kepler 1997, 330).

Finally, Kraft turns to the explanation of his prediction on the ice drift on the Neva River and opens as he made his decision: he studied all the dates, when the ice started drift during several years and analysed every planetary aspect, which took place during these periods. Then he listed all strong aspects that had to occur during the suitable period. He focused his attention on the two aspects: trine of Jupiter to Venus and opposition of Venus and Mars. He had chosen opposition of Mars to Venus that happened on the 20 April. However, the ice started drift on 16 April, when the trine aspect of Jupiter and Venus took place and although the mistake is not big, still the nature proves stronger action of Jupiter-Venus configuration (1732, 261).

Figure 5. Kraft on the ice drift: 20 April 1732.

However, Kraft, following Kepler in his theory and method, presents his own independent research, based on his own material, observations and analysis. He tests Kepler’s methodology of the astrological meteorological forecast and offers his own study of the subject. Though his conclusion did not come out exact, he made corrections to his analysis and suggested a different option, opening the process up to continuous research. Thus, Kraft demonstrates application of Kepler’s concepts and validates them by this own study.


The textual analysis of Kraft’s article and Kepler’s treatises Harmonices Mundi and On the More Certain Fundamentals of Astrology demonstrates that Kraft’s material repeats Kepler’s arguments and even the composition of the latter text.  It relies on Kepler’s theory of aspects and their connection to the musical harmony and human soul. Kraft’s method of astrological-meteorological prognostication is based on Kepler’s innovative theory and method. This method rests on constant meteorological observation and collection of the astrological data, connected to the meteorological events, critical analysis and comparison of it for further research.

Kraft’s philosophical discussion concerning astrology establishes dialogic connection with not only Kepler’s ideas and theory, but places his arguments into the discussion with Giovanni Pico della Mirandola and bridges his ideas to those expressed by Ptolemy.

Kraft undertakes his own astrological meteorological research and builds his experimental study relying on Kepler’s methods, testing and validating them. 



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