Johannes Kepler, the last Western astronomer of note to believe in astrology, was born on January 6, 1571, in Weil, Württemberg, Germany. He studied the elliptical orbits of the planets and discovered the three laws of planetary motion that were to lead to Newton's law of universal gravitation. In 1600, Kepler became assistant to Tycho Brahe, succeeding him as court astronomer to Rudolf II. Kepler was deeply mystical, and many of his astronomical discoveries were motivated by a desire to demonstrate that a neoplatonic/Pythagorean mathematical order governed the heavens.
The son of peasants, Kepler erected horoscopes and published almanacs to supplement his income as court astronomer. On the title page of De fundamentis, Kepler inscribed, "Discover the force of Heavens O Men: once recognized it can be put to use." He asserted that astrological influence "is so convincing that it can be denied only by those who had not examined it." He also said, "We cannot deny the influence of the stars, without disbelieving in the wisdom of God."
In much the same way as Saint Thomas Aquinas, Kepler felt that human beings could rise above planetary influences. As do contemporary astrologers, he thus cast his predictions in terms of tendencies and probabilities rather than in terms of absolute fate. Kepler's contribution to astrology was his general theory of aspects, and he also invented the quintile, the biquintile, and the sesquiquadrate. Kepler died November 15, 1630.
Kepler is well known to modern science as the discoverer of the three laws of planetary motion named after him. His achievements were momentous, coming on the heels of the Copernican revolution and creating an astronomy of the solar system that was vastly superior to that existing before.
As an astrologer, Kepler's achievements were equally, if not more, substantial. Like his contemporary, Shakespeare, he was "myriad minded." His thinking ranged from the most traditionally Judeo-Christian and Pythagorean in his mysticism, to the most astonishingly modern in his more scientific thinking modes. Full of apparent contradictions, he was in reality the most complex of thinkers in astronomy and astrology, and yet, in some ways, was fundamentally quite consistent. Furthermore, he was a superb writer—lucid and simple, and capable of describing great intricacies clearly, as well as clothing some of his thoughts in magnificent poetic metaphors.
The supposed separation of astronomy and astrology is actually an illusion as far as Kepler was concerned. The contemporary scientific community in particular has all too often been the victim of this illusion, and has oversimplified Kepler's alleged "attacks" on astrology, which are actually heated objections to "bad" astrology and nothing more. The following in particular is a case in point, from his Tertius Interveniens:
This curiosity [about astrology] flourishes, and stimulates one to learn astronomy. And astronomy is not rejected, but highly praised, as is appropriate. Now this Astrology is a foolish daughter.. But dear Lord, what would happen to her mother, the highly reasonable Astronomy, if she did not have this foolish daughter. The world, after all, is much more foolish, indeed is so foolish, that this old sensible mother, Astronomy, is talked into things and put to the lie as a result of her daughter's foolish pranks.. The mathematician's pay would be so low, that the mother would starve, if the daughter did not earn anything.
As devastating as this may seem to astrologers, the passage is not really a condemnation of all astrology. His thoughts must be understood to mean the popular forms of astrology, which he condemned unequivocally.
As for the accusation that astronomers would starve if they did not do horoscopes for pay—this may have some truth in it, but it does not mean that Kepler had to cheapen his science of astronomy by using the popular astrology of "the daughter." And he did cast and interpret horoscopes for pay, but his astrology is on a very high level indeed, as is shown by the two extant delineations of Generalisimus Wallen-stein's birth chart (1608 and 1625), and others.
And such astrology was, for Kepler, to be included under astronomy. This astrology/astronomy was Kepler's true vocation up to the point in 1619 when he transcended it, but still made it part of a greater scheme of the universe that he called Harmonice Mundi (World Harmony), the title of his last major book (1619). Even after then, he still spoke of astrology in these terms, as noted in Die Astrologie des Johannes Kepler: "Philosophy, and therefore genuine astrology, is a testimony of God's works and is therefore holy. It is by no means a frivolous thing. And I, for my part, do not wish to dishonor it." That this "genuine astrology" was effective is well proven by the fact that Kepler predicted the manner and time of Wallenstein's death well in advance.
Many astrologers will at first feel offended by Kepler. He was as outspoken against some astrologers as he was against those who condemned astrology. This is seen mainly in his 1610 book Tertius Interveniens (Third Party Intervening), in which he takes a "third party" position between those who flatly condemn astrology and those who accept as true everything said in its name. He draws sharp lines between his perceptions of genuine and false practices of the art.
Like Friedrich Nietzsche, his fellow countryman of three centuries later, Kepler was a thinker who skillfully required readers to ponder issues thoroughly while being challenged, irritated, even infuriated. This process is so valuable in helping to gain ever deeper insights. It is advisable at times, when he is attacking with fury, to keep in mind that, like his earlier fellow countryman, Martin Luther, he was a reformer. He definitely did not propose that astrology be abolished, any more than Luther intended to destroy Christianity.
The foundation of his astrology was geometry and, more widely, a universal harmony present in geometry, as demonstrated in Tertius Interveniens: "Within this lower world a spiritual nature is concealed that can operate through geometry, which is vitalized through the geometrical and harmonic connections____"; "The geometry or harmony of aspects is not between the stars in the sky, but is located rather down here on earth in the point that collects all their rays." This principle led him to his specific contributions to astrology, among which are: his analysis of planetary interrelationships through Platonic solids; his discovery of additional aspects (the quintile and semisquare); and his cataloging and comments on the fixed stars. Beyond these accomplishments, his theory and philosophy of are indeed major contributions.
Brau, Jean-Louis, Helen Weaver, and Allan Edmands. Larousse Encyclopedia of Astrology. New
York: Plume, 1980. Kepler, Johannes. Harmonices Mundi. -. Tertius Interveniens.
Kitson, Annabella, ed. History and Astrology: Clio and Urania Confer. London: Mandala, 1989.
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