Kepler achieved much in his lifetime, from theories on geometry, astrology and cosmology, to making progress in such areas as science and mathematics, optics, the discovery of two new polyhedra, work on the golden ratio and theories on the packing of spheres.

Kepler is mostly remembered for his three laws of planetary motion but he is seen as central to the intellectual transformation from medieval thinking to the modern approach of the enlightenment.

*The Life & Thinking Of Kepler*

Johannes Kepler’s father was killed in battle as a mercenary and his mother raised him in Stuttgart, Germany where he was born in 1571, his mother being a healer and herbalist. In 1577 his mother took him to see the Great Comet eclipse at the tender age of six. Kepler was trained as a Lutheran in a ministry, excelling in mathematics and subsequently taking up a post teaching astronomy and mathematics at the University of Graz in Austria. Kepler had also read the 1543 published work of Copernicus, *De Revolutionibus*, and was convinced that the Earth revolved around the sun – a dangerous view to hold in the 16th and 17th centuries, much like Galileo & Descartes, he too, would be no stranger to suffering because of it. His mother was tried for witchcraft, though it probably had more to do with his Copernican views.

This did not slow Kepler though, as his logical and rhetorical methods influenced the thinking of the 16th century, he rejected the backwards thinking of his time and led the intellectual transformation that we call *The Enlightenment*. When he refused to convert to Catholicism, he was promptly expelled from his post at Graz and more harshly, from Austria. Rendering him unemployed for his views and beliefs.

Over many years he maintained a correspondence with one Tycho Brahe whom I have done a short piece on which you can find below

Although Brahe did not share Kepler’s views, he valued his research nonetheless, referring to his ‘detailed and precise astronomical observations’ which impressed him so much that he hired him as an assistant in Prague. One of his most impressive works describes Platonic solids, a series of nested orbs, wherein each Platonic solid was inscribed and circumscribed by a sphere, he related these to the movement of the planets, seeing them as God’s geometric plan for the universe. This major work published in 1596 and titled *Mysterium Cosmographicum* [ The Mysteries Of The Universe ] was his first, his second work published in 1609 detailed his first law of planetary motion, their elliptical motions, with the sun being their focus of course. He developed his theories of the golden rectangle and wrote that geometry has two great treasures, one being the theorem of Pythagoras & the other the division of a line into extreme and mean ratio.

An example of a *Nested Sphere*

In 1619 Kepler began to relate his thoughts on the proportions of the natural world to music and explored the properties of regular polygons and regular solids, in a book called *Harmonices Mundi* [ The Harmony Of The Worlds ] this along with the Rudolphine Tables so named after Emperor Rudolph II and published in 1627 though being a catalogue of stars and planets and their movements was prohibited during the Catholic Counter-Reformation period.

Upon the death of Brahe Kepler was appointed the post of Imperial Mathematician to the Emperor where he also developed his laws of planetary motion and the golden ratio, in 1610 he engaged in dialogue with Galileo about the ‘four satellites of Jupiter’. When his wife died in 1611, it moved him deeply emotionally and physically he moved to Linz in 1612 to continue his work on astrology. He died in 1630.