The Sleepwalkers

Here’s a fact for the day: February 4th 1600, two of our era’s most influential men met for the very first time, at Benatek Castle near Prague. Tycho de Brahe, a Danish grand seigneur whose greatest discovery was that astronomy needed precise and continuous observational data and who had accordingly assembled the world’s most impressive collection of instruments for planetary observation, and Johannes Kepler, a myopic, somewhat hypochondriac German peasant, genius and stargazer, who benefitted from inheriting all of Tycho’s meticulous observations months after having met him.

That we now fixedly believe that the earth and planets revolve around the sun at the centre of the solar system was by no means the case throughout history, as I am now learning through Arthur Koestler’s excellent book The Sleepwalkers. Although thousands of years ago a handful of talented philosophers had ventured to imagine our cosmos as being other than a geocentric system, their wisdom was somehow lost. Aristarchus, born in 310 B.C. and last in a line of Pythagorean astronomers, had carried out the development which started with Pythagoras and continued by his disciples to its logical conclusion: that the sun, not the earth, was the centre of our world around which all planets revolve.

But here the development comes to an abrupt end. Aristarchus had no disciples and found no followers. For nearly two millennia the heliocentric system was forgotten - or, shall one say, repressed from consciousness? - until an obscure Canon in Varmia, a remote outpost in Christendom, picked up the thread where the Samian had left off.

That obscure Canon was the timid Nicolas Copernicus whose seminal book On the Revolutions of the Heavenly Spheres at last resurrected that daft doubt that the earth mightn’t be the centre of the universe, to posit that the planets might well revolve around the sun. If it weren’t for a certain George Joachim Rheticus however, that book would most likely have never seen the light of day. It was after the young Astronomy Professor’s persistent, endless cajoling that, after almost 30 years of delay, Copernicus reluctantly allowed the manuscript to be first read by his young disciple, then written about - only then was Rheticus permitted to copy out all 424 pages of the manuscript in small handwriting and at last, in 1542, brought On the Revolutions to the printers.

Copernicus’ book allowed for heliocentrism to slowly come back on astronomers’ radar although in his system the planets were not centered on the sun but a point near the sun (at least he got the bit about the earth being in movement right). Slowly, because the book made little effect on the world at the time, so entrenched it was in its old ways. It took another half-century for the ideas implicit in On the Revolutions to take their full effect in the persona of Johannes Kepler. And it was only thanks to Tycho that the young Kepler was able to gain the precise data he so craved to create his cosmology. Not the imagined one of epicycles and perfect circles of the ancients, but one that would withstand the test of verifiable observation. Kepler truly represented the watershed - that jump from metaphysical speculation to empirical science - the only man capable of throwing away his previous theories in the light of facts. As he begins the second chapter of his Mysterium:

What we have so far said served merely to support our thesis by arguments of probability. Now we shall proceed to the astronomical determination of the orbits and to geometrical considerations. If these do not confirm our thesis, then all our previous efforts have doubtless been in vain.

It is characteristic of Kepler that in the event, some of the data did not fit the theory: the observed positions of the planets (in this case, the pestilent Mars) differed from those which his theory demanded by magnitudes of up to eight minutes arc. Both Ptolemy and Copernicus wouldn’t have found this troublesome: their observations were only accurate within a margin of ten minutes.

But for us, who, by divine kindness were given an accurate observer such as Tycho Brahe, for us it is fitting that we should acknowledge this divine gift and put it to use [...] Henceforth I shall lead the way towards that goal according to my own ideas. For, if I had believed that we could ignore these eight minutes, I would have patched up my hypothesis accordingly. But since it was not permissible to ignore them, those eight minutes point the road to a complete reformation of astronomy: they have become the building material for a large part of this work...

As Koestler puts it:

This new departure determined the climate of European thought in the last three centuries, it set modern Europe apart from all other civilizations in the past and present, and enabled it to transform its natural and social environment as completely as if a new species had arisen on this planet.

An eight minutes arc! Why so much fuss?! While Koestler attributes it to Kepler’s introduction of physical causality to the geometry of the skies it wouldn’t be absurd to think that Kepler’s reverence for Tycho’s obstinate diligence mightn’t have something to do with it too.

At last then, on 4 February 1600, Tycho de Brahe and Johannes Keplerus, co-founders of a new universe, met face to face, silver nose to scabby cheek. Tycho was fifty-three, Kepler twenty-nine. Tycho was an aristocrat, Kepler a plebeian; Tycho a Croesus, Kepler church-mouse; Tycho a Great Dane, Kepler a mangy mongrel. They were opposites in every respect but one: the irritable, choleric disposition which they shared. The result was a constant friction, flaring into heated quarrels, followed by half-hearted reconciliations.

But all this was on the surface. In appearance, it was a meeting of two crafty scholars, each determined to make use of the other for his own purposes. But under the surface, they both knew, with the certainty of sleepwalkers, that they were born to complete each other; that it was the gravity of fate which had drawn them together. Their relationship was to alternate all the time between these two levels: qua sleepwalkers, they strolled arm in arm through uncharted spaces; in their waking contacts they brought out the worst in the other’s character, as if by mutual induction.

As Koestler says of Rheticus’ meeting with Copernicus, “it was one of the great encounters of history, and ranks with the meetings of Aristotle and Alexander, Cortes and Montezuma, Marx and Engels.” The earth would have certainly had a different face had any of these meetings not taken place - and how uncertain their fate was decided!

Had Tycho remained in Denmark, it is highly unlikely that Kepler could have afforded the expense to visit him during the short remaining span of Tycho’s life [who was to die the following year]. The circumstances which made them both exiles, and guided them towards their meeting, can be attributed to coincidence or providence, according to taste, unless one assumes the existence of some hidden law of gravity in History. After all, gravity in the physical sense is also merely a word for an unknown force acting at a distance.

It makes one wonder at how future generations will look back onto our times and laugh at our fixations and certainties, and stand in awe at those moments in which certainty, against all the odds, was thrown away, ignored, repressed in favor of something else. Some higher calling, the empirical mind, an urge to discover anew - whatever you want to call it. That seems, to me, to be the two threads which explain so well what humans have always done: held on to the security of the known and struggled to let go - at times, succeeding, if only by sleepwalking.