Sunday, August 31, 2008

Quote of the Day

Copernicus knew that his ideas could be seen by his contemporaries as removing the sun from the heavens and depositing it in the lowest, least exalted place: in the dead center of the universe. According to prevailing Aristotelian natural philosophy, the cosmic center was where heavy -- and by extension ignoble -- things collected. As one influential philosopher had expressed it in the previous century, the center represented 'the excrementary and filthy parts of the lower world.'

Anticipating the charge that he was dishonoring the sun, Copernicus deftly reconstrued the center as a place of honor and of effective, efficient government. Using a poetic play on words, he imagined it as a throne (solium) fit for the sun (sol). With the sun in the center, the pathways of the planets at last made sense; they displayed marvelous symmetry and harmonious connection; they exemplified the sort of beauty that something called a cosmos ought to embody: The sun's and the planets' astronomical truth reflected poetic truth and, in a profound sense, also poetic justice and decorum.

In the First Account Rheticus used the same governmental analogy to support the Copernican claim that the sun is at rest, that it does not move about like a planet. 'My teacher ... is aware that in human affairs the emperor need not himself hurry from city to city in order to perform the duty imposed on him by God.' The centrality and immobility of the sun in Copernicus's system were therefore perfectly consistent with -- and were indeed essential to -- the sun's dignity and its proper governance of the planets. As Rheticus declared, 'While we were unable from our common theories even to infer this rule by the sun in the realm of nature, we ignored most of the ancient encomia of the sun as if they were merely poetry.'

But the encomia -- the songs of praise -- were nothing less than poetry, and in fact turned out to be not distractions from reality but signposts pointing toward it. The similes and metaphors of the sun as ruler were themselves clues to the real physical structure of the sun and the universe. Copernicus's system did imply that the sun occupies literally the lowest possible cosmic location -- that, in Rheticus's words, it 'has descended to the center of the universe.' Nevertheless, the fitness, beauty, and the glory of the sun in this reconfigured cosmos more than compensated for that lowering. In the First Account Rheticus expressed that glory in explicitly poetic form.

Thus God stationed in the very midst of this theater his governor of nature, king of the entire universe, conspicuous by its divine splendor, the sun
To whose rhythm the gods move, and the world
Receives its laws and keeps the pacts ordained.
"Having exchanged places with the sun, the earth was now risen in the world, promoted to the status of a 'star,' and 'move[d] among the planets as one of them.' As Galileo would later declare, earth was no longer 'excluded from the dance of the stars.' Rheticus and Copernicus together achieved the monumental feat of raising the status of both earth and sun within the same bold cosmology.

Dennis Danielson
The First Copernican: Georg Joachim Rheticus and the Rise of the Copernican Revolution

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