Johannes Kepler, Keppler, Khepler, Kheppler, or Keplerus was conceived on 16 May A.D. 1571, at 4.37 a.m., and was born on 27 December at 2.30 p.m., after a pregnancy lasting 224 days, 9 hours and 53 minutes. The five different ways of spelling his name are all his own, and so are the figures relating to conception, pregnancy, and birth, recorded in a horoscope which he cast for himself. The contrast between his carelessness about his name and his extreme precision about dates reflects, from the very outset, a mind to whom all ultimate reality, the essence of religion, of truth and beauty, was contained in the language of numbers.
On re-reading this opening paragraph of the Kepler chapters in Arthur Koestler’s The Sleepwalkers of 1959, I have no trouble perceiving what once made me, a 17-year old, aspiring history student with a high-school science major, read on, and on, and on. Certainly the catching, not to say gripping style. Almost certainly as well, albeit more dimly so, the virtuoso manner in which two brilliantly chosen, telling details are within the space of just three sentences being amplified into a sweeping characterization of the personality whose life and works remain from here on the author’s principal subject for some two hundred pages to come.