o would one day capture a little of that galactic light； and try to puzzle out what had sent it on its way。
And after the Earth dies； some 5 billion years from now； after it is burned to a crisp or even swallowed by the Sun； there will be other worlds and stars and galaxies ing into being—and they will know nothing of a place once called Earth。
IT ALMOST NEVER FEELS like prejudice。 Instead； it seems fitting and just—the idea that； because of an accident of birth； our group （whichever one it is） should have a central position in the social universe。 Among Pharaonic princelings and Plantagenet pretenders； children of robber barons and Central mittee bureaucrats； street gangs and conquerors of nations； members of confident majorities； obscure sects； and reviled minorities； this self…serving attitude seems as natural as breathing。 It draws sustenance from the same psychic wellsprings as sexism； racism； nationalism； and the other deadly chauvinisms that plague our species。 Unmon strength of character is needed to resist the blandishments of those who assure us that we have an obvious； even God…given； superiority over our fellows。 The more precarious our self…esteem； the greater our vulnerability to such appeals。
Since scientists are people； it is not surprising that parable pretensions have insinuated themselves into the scientific worldview。 Indeed； many of the central debates in the history of science seem to be； in part at least； contests over whether humans are special。 Almost always； the going…in assumption is that we are special。 After the premise is closely examined； though； it turns out—in dishearteningly many cases—that we are not。
Our ancestors lived out of doors。 They were as familiar with the night sky as most of us are with our favorite television programs。 The Sun； the Moon； the stars； and the planets all rose in the east and set in the west； traversing the sky overhead in the interim。 The motion of the heavenly bodies was not merely a diversion； eliciting a reverential nod and grunt； it was the only way to tell the time of day and the seasons。 For hunters and gatherers； as well as for agricultural peoples； knowing about the sky was a matter of life and death。
How lucky for us that the Sun； the Moon； the planets； and the stars are part of some elegantly configured cosmic clockwork！ It seemed to be no accident。 They were put here for a purpose； for our benefit。 Who else makes use of them？ What else are they good for？
And if the lights in the sky rise and set around us； isn't it evident that we're at the center of the Universe？ These celestial bodies—so clearly suffused with unearthly powers； especially the Sun on which we depend for light and heat—circle us like courtiers fawning on a king。 Even if we had not already guessed； the most elementary examination of the heavens reveals that we are special。 The Universe seems designed for human beings。 It's difficult to contemplate these circumstances without experiencing stirrings of pride and reassurance。 The entire Universe； made for us！ We must really be something。
This satisfying demonstration of our importance； buttressed by daily observations of the heavens； made the geocentrist conceit a transcultural truth—taught in the schools； built into the language； part and parcel of great literature and sacred scripture。 Dissenters were discouraged； sometimes with torture and death。 It is no wonder that for the vast bulk of human history； no one questioned it。
It was doubtless the view of our foraging and hunting ancestors。 The great astronomer of antiquity； Claudius Ptolemaeus （Ptolemy）； in the second century knew that the Earth was a sphere； knew that its size was 〃a point〃 pared to the distance of the stars； and taught that it lay 〃right in the middle of the heavens。〃 Aristotle； Plato； St。 Augustine； St。 Thomas Aquinas； and almost all the great philosophers and scientists of all cultures over the 3；000 years ending in the seventeenth century bought into this delusion。 Some busied themselves figuring out how the Sun； the Moon； the stars； and the planets could be cunningly attached to perfectly transparent； crystalline spheres—the big spheres； of course； centered on the Earth—that would explain the plex motions of the celestial bodies so meticulously chronicled by generations of astronomers。 And they succeeded： With later modifications； the geocentric hypothesis adequately accounted for the facts of planetary motion as known in the second century； and in the sixteenth。
From there it was only a slight extrapolation to an even more grandiose claim—that the 〃perfection〃 of the world would be inplete without humans； as Plato asserted in the Timaeus。 〃Man 。 。 。 is all；〃 the poet and cleric John Donne wrote in 1625。 〃He is not a piece of the world； but the world itself； and next to the glory of God； the reason why there is a world。〃
And yet—never mind how many kings； popes； philosophers； scientists； and poets insisted on the contrary—the Earth through those millennia stubbornly persisted in orbiting the Sun。 You might imagine an uncharitable extraterrestrial observer looking down on our species over all that time—with us excitedly chattering； 〃The Universe is created for us！ We're at the center！ Everything pays homage to us！〃—and concluding that our pretensions are amusing； our aspirations pathetic； that this must be the planet of the idiots。
But such a judgment is too harsh。 We did the best we could。 There was an unlucky coincidence between everyday appearances and our secret hopes。 We tend not to be especially critical when presented with evidence that seems to confirm our prejudices。 And there was little countervailing evidence。
In muted counterpoint； a few dissenting voices； counseling humility and perspective； could be heard down through the centuries。 At the dawn of science； the atomist philosophers of ancient Greece and Rome— those who first suggested that matter is made of atoms—Democritus； Epicurus； and their followers （and Lucretius； the first popularizer of science） scandalously proposed many worlds and many alien life forms； all made of the same kinds of atoms as we。 They offered for our consideration infinities in space and time。 But in the prevailing canons of the West； secular and sacerdotal； pagan and Christian； atomist ideas were reviled。 Instead； the heavens were not at all like our world。 They were unalterable and 〃perfect。〃 The Earth was mutable and 〃corrupt。〃 The Roman statesman and philosopher Cicero summarized the mon view： 〃In the heavens 。 。 。 there is nothing of chance or hazard； no error； no frustration； but absolute order； accuracy； calculation and regularity。〃
Philosophy and religion cautioned that the gods （or God） were far more powerful than we； jealous of their prerogatives and quick to mete out justice for insufferable arrogance。 At the same time； these disciplines had not a clue that their own teaching of how the Universe is ordered was a conceit and a delusion。
Philosophy and religion presented mere opinion—opinion that might be overturned by observation and experiment—as certainty。 This worried them not at all。 That some of their deeply held beliefs might turn out to be mistakes was a possibility hardly considered。 Doctrinal humility was to be practiced by others。 Their own teachings were inerrant and Infallible。 In truth； they had better reason to be humble than they knew。
BEGINNING WITH COPERNICUS in the middle sixteenth century； the issue was formally joined。 The picture of the Sun rather than the Earth at the center of the Universe was understood to be dangerous。 Obligingly； many scholars were quick to assure the religious hierarchy that this newfangled hypothesis represented no serious challenge to conventional wisdom。 In a kind of split…brain promise； the Sun…centered system was treated as a mere putational convenience； not an astronomical reality that is； the Earth was really at the center of the Universe； as everybody knew； but if you wished to predict where Jupiter would be on the second Tuesday of November the year after next； you were permitted to pretend that the Sun was at the center。 Then you could calculate away and not affront the Authorities。*
* Copernicus' famous book was first published with an introduction by the theologian Andrew Osiander； inserted without the knowledge of the dying astronomer。 Osiander's well…meaning attempt to reconcile religion and Copernican astronomy ended with these words： 〃＇L＇et no one expect anything in the way of certainty of astronomy； since astronomy can offer us nothing certain； lest； if anyone take as true that which has been constructed for 。mother use； he go away from this discipline a bigger fool than w hen he cane to it。〃 Certainty could be found only in religion。
〃This has no danger in it；〃 wrote Robert Cardinal Bellarmine； the foremost Vatican theologian in the early seventeenth century； and suffices for the mathematicians。 But； to affirm that the Sun is really fixed in the center of the heavens and that the Earth revolves very swiftly around the Sun is a dangerous thing； not only irritating the theologians and philosophers； but injuring our holy faith and making the sacred scripture false。〃
〃Freedom of belief is pernicious；〃 Bellarmine wrote on another occasion。 〃It is nothing but the freedom to be wrong。〃
Besides； if the Earth was going around the Sun； nearby stars should seem to move against the background of more distant stars as； every six months； we shift our perspective from one side of the Earth's orbit to the other。 No such 〃annual parallax〃 had been found。 The Copernicans argued that this was because the stars were extremely far away—maybe a million times more distant than the Earth is from the Sun。 Perhaps better telescopes； in future times； would find an annual parallax。 The geocentrists considered this a desperate attempt to save a flawed hypothesis； and ludicrous on the face of it。
When Galileo turned the first astronomical telescope to the sky； the tide began to turn。 He discovered that Jupiter had a little retinue of moons circling it； the inner ones orbiting faster than the outer ones； just as Copernicus had deduced for the motion of the planets about the Sun。 He found that Mercury and Venus went through phases like the Moon （showing they orbited the Sun）。 Moreover； the cratered Moon and the spotted Sun challenged the perfection of the heavens。 This may in part constitute the sort of trouble Tertullian was worried about thirteen hundred years earlier； when he pleaded； 〃If you have any sense or modesty； have done with prying into the regions of the sky； into the destiny and secrets of the universe。〃
In contrast； Galileo taught that we can interrogate Nature by observation and experiment。 Then； 〃facts which at first sight seem improbable will； even on scant explanation； drop the cloak which had hidden them and stand forth in naked and simple beauty。〃 Are not these facts； available even for skeptics to
confirm； a surer insight into God's Universe than all the speculations of the theologians？ But what if these facts contradict the beliefs of those who hold their religion incapable of making mistakes？ The princes of the Church threatened the aged astronomer with torture if he persisted in teaching the abomin