Department of History
University of California, Irvine
Instructor:    Dr. Barbara J. Becker

Lecture 7. Seeing and Believing.

Response to the Copernican System
from The Week, or Creation of the World (1578)
 by Guillaume du Bartas (1544-1590)

... some brain-sicks live there now-a-days,
That lose themselves still in contrary ways;
Prepostrous wits that cannot row at ease,
On the Smooth Channel of our common Seas.

And such are those (in my conceit at least)
Those Clerks that think (think how absurd a jest)
That neither Heav'ns nor Stars do turn at all,
Nor dance about this great round Earthy Ball;
But th'Earth itself, this Massy Globe of ours,
Turns roundabout once every twice-twelve hours:
And we resemble Land-bred Novices
New brought aboard to venture on the Seas;
Who, at first launching from the shore, suppose
The ship stands still, and that the ground it goes.

So twinkling Tapers, that Heav'n's Arches fill,
Equally distant should continue still.
So never should an arrow, shot upright,
In the same place upon the shooter light;
But would do (rather) as (at Sea) a stone
Aboard a Ship upward uprightly thrown;
Which not within-board falls, but in the Flood
A-stern the Ship, if so the Wind be good.

So should the Fowls that take their nimble flight
From Western Marches towards Morning's light;
And Zephyrus, that in summer time
Delights to visit Eurus in his clime;
And bullets thundered from the cannon's throat
(Whose roaring drowns the Heav'nly thunder's note)
Should seem recoil:  sithens the quick career,
That our round Earth should daily gallop here, 
Must needs exceed a hundred fold (for swift)
Birds, Bullets, Winds; their wings, their force, their drift.

Arm'd with these Reasons, 'twere superfluous
T'assail the Reasons of Copernicus;
Who to salve better of the Stars th'appearance
Unto the Earth a three-fold motion warrants:
Making the Sun the Center of this All,
Moon, Earth, and Water, in one only Ball.
But sithence here, nor time, nor place doth suit,
His Paradox at length to prosecute;
I will proceed, grounding my next discourse
On the Heav'ns motions, and their constant course.

from The Apology for Raimond de Sebonde (1580)
by Michel de Montaigne (1533-1592)

[Natural] philosophy is nothing but sophisticated poetry.... 

Just as women use false teeth when their real ones drop out, and in place of a natural complexion lay on a manufactured one, and round out their figures with cotton stuffing, so ... science pays us with hypotheses which it confesses are pure invention. 

These epicycles with which astronomy moves the stars are merely the best devices it can contrive.... 

It was the stars and the heavens that were in motion for three thousand years.  Or so everyone believed.... 

Now, in our time, Copernicus has so firmly established [that the earth moves, not the stars] that it serves everything we can observe astronomically. 

What shall we conclude from this, except that it is hardly worth while to heat ourselves up over one or the other?  Who knows but what in a thousand years from now a third opinion will not supplant them both?

[As Lucretius has written (Book V, On the Nature of Things:]

Thus time as it goes round changes the seasons of things.  That which was in esteem, falls at length into utter disrepute; and then another thing mounts up and issues out of its degraded state and every day is more and more coveted and blossoms forth high in honor when discovered and is in marvellous repute with men.

from Theater of Universal Nature (1597)
Jean Bodin (1520-1596)

No one in his sense, or imbued with the slightest knowledge of physics, will ever think that the earth, heavy and unwieldy from its own weight and mass, staggers up and down around its own center and that of the sun; for at the slightest jar of the earth, we would see cities and fortresses, towns and mountains thrown down.... 

For if the earth were to be moved, neither an arrow shot straight up, nor a stone dropped from the top of a tower would fall perpendicularly, but either ahead or behind.... 

Lastly, all things on finding places suitable to their natures, remain there, as Aristotle writes.  Since therefore the earth has been allotted a place fitting its nature, it cannot be whirled around by other motion than its own.

A Perfit description of the Cælestiall Orbes according to the most auncient doctrine of the Pythagoreans, latelye reuiued by Copernicus and by Geometricall Demonstrations approued (1576)

Thomas Digges (c.1546-1595)

To The Reader

Having of late (gentle reader) corrected and reformed sundry faults that by negligence in printing have crept into my father's General Prognostication, among other things I found a description or Model of the world, and situation of Spheres Celestial and Elementary, according to the doctrine of Ptolemy, whereunto all Universities (led thereto chiefly by the authority of Aristotle) have ever since then consented.  But in this our age, one rare wit (seeing the continual errors that from time to time more and more have been discovered...) has by long study, painful practice, and rare invention delivered a new Theory or model of the world, showing that the Earth rests not in the Center of the whole world, but only in the Center of this our mortal world or Globe of Elements, which environed and enclosed in the Moon's Orbit, and together with the whole Globe of mortality, is carried yearly round about the Sun, which like a king in the midst of all reigneth and gives laws of motion to the rest, spherically dispersing his glorious beams of light through all this sacred Celestial Temple.  And the earth itself to be one of the Planets ... turning every 24 hours round upon his own Center, whereby the Sun and great Globe of fixed stars seem to sway about and turn, albeit in deed they remain fixed. 

So many ways is the sense of mortal men abused, but reason and deep discourse of wit having opened these things to Copernicus ... I thought it convenient ... to publish this, to the end such noble English minds (as delight to reach above the baser sort of men) might not be altogether defrauded of so noble a part of Philosophy.  And to the end it might manifestly appear that Copernicus meant not as some have fondly accused him, to deliver these grounds of the Earth's mobility only as Mathematical principles, feigned and not as Philosophical truly averred.... 

Why shall we so much dote in the appearance of our senses, which many ways may be abused, and not suffer our selves to be directed by the rule of Reason, which the great GOD has given us as a Lamp to lighten the darkness of our understanding, and the perfect guide to lead us to the golden branch of Verity amid the Forest of errors.... 

And let us not in matters of reason be led away with authority and opinions of men....

The Globe of Elements enclosed on the Orbit of the Moon I call the Globe of Mortality because it is the peculiar Empire of death.  For above the Moon they fear not his force....

In the midst of this Globe of Mortality hangs this dark star or ball of earth and water, balanced and sustained in the midst of the thin air only with that propriety which the wonderful workman hath given at the Creation to the Center of this Globe, with his magnetical force vehemently to draw and [pull forcibly] unto itself all such other Elemental things as retain the like nature.  This ball, every 24 hours by natural, uniform and wonderful sly and smooth motion rolls round, making with his Period our natural day, whereby it seems to us that the huge infinite immoveable Globe [i.e., the sphere of the fixed stars] should sway and turn about. 

The Moon's Orbit, that houses and contains this dark star and the other mortal, changeable, corruptible Elements & Elementate things is also turned round every 29 days 31 minutes 50 seconds ... and this period may most aptly be called the Month.  The rest of the Planets' motions appear by the Picture, and shall more largely be hereafter spoken of.

Herein, good Reader,... I mean though not as a Judge to decide, yet at the mathematical bar in this case to plead, in such sort as it shall manifestly appear to the World whether it be possible upon the Earth's stability to deliver any true or probable Theory and then refer the pronouncing of sentence to the grave Senate of indifferent discreet Mathematical Readers. 

Farewell, and respect my travail as you shall see them tend to the advancement of truth and discovering the Monstrous loathsome shape of error.

Tycho Brahe (1546-1601)
attended University of Copenhagen
participated in duel in which he lost part of his nose
observed New Star in the constellation Cassiopeia

concluded it is not an atmospheric phenomenon, but rather is located in the celestial realm

attended coronation of Holy Roman Emperor, Rudolph II

forged friendship that would prove useful later

awarded island of Hveen by Danish king

established scientific research center at Uraniborg

acquired array of fine astronomical instruments (including his renowned mural quadrant) with which he carries out years of painstaking observation and celestial mapping

thanks to royal patronage, able to embark on long-term observation projects:

  • mapping the fixed stars with precision
  • observing and recording the changing positions of the planets against the fixed stars
observed comet

concluded it is also located in the celestial realm

after disagreement with Danish king, left Denmark for court of Rudolph II in Prague
Johannes Kepler (1571-1630)

A Verbal Self-Portrait

That man has in every way a dog-like nature.  His appearance is that of a little lap-dog.  His body is agile, wiry and well-proportioned....

He was constantly on the move, ferreting among the sciences, politics and private affairs, including the lowest kind; always following someone else, and imitating his thoughts and actions....

[H]e grieved that on account of the impurity of his life, the honor to be a prophet was denied him....

In this man there are two opposite tendencies:  always to regret any wasted time, and always to waste it willingly....

Notable Events in Kepler's Life

1571 (May 16, 4.37 am)
1571 (Dec 27, 2.30 pm)
born at Weil-der-Stadt
entered University of Tubingen

received Master's degree 

began work as mathematics instructor at Gratz

formulated "fourth law"--
six planetary orbits are nested in five Platonic solids

Conjunctions of Saturn and Jupiter (1300-1490)

Right Ascension
hrs        mins
 1.   4-1306
13    50
 2.   5-1324
 5    10
 3.   3-1345
23    30
 4. 10-1365
14    20
 5. 10-1384
 6    00
 6.   1-1405
21    50
 7.   3-1425
15    00
 8.   7-1444
Gemini  6    45
 9.   4-1464 Aquarius 22    30
10. 11-1484 Libra/Scorpio 15    30

Conjunctions of Saturn and Jupiter (1300-1490)
depicted graphically

Conjunctions of Saturn and Jupiter (1570-1770)

Right Ascension
hrs        mins
   1.   5-1583
23    30
   2. 12-1603
16    30
   3.   7-1623
 8    40
   4.  2-1643
14    20
   5.  4-1663
17    00
   6.   2-1683
 9    10
   7.   5-1702
 0    30
  8.   1-1723 Scorpio/Sagittarius 17    40
  9.   8-1742 Leo 10    00
10.  3-1762 Pisces  0    50

Conjunctions of Saturn and Jupiter (1570-1770)
depicted graphically by Kepler

Kepler's "Fourth Law"
Mercury Venus Earth Mars Jupiter Saturn

Notable Events in Kepler's Life (cont'd)

published Mysterium Cosmographicum (Cosmic Mystery)
accepted position at Prague with Tycho
began work on problem of Mars' orbit
death of Tycho
formulated "second law"--
planets sweep out equal areas in equal times
formulated "first law"--
planets move in elliptical orbits
observed another New Star in the constellation Ophiuchus
published Astronomia Nova (New Astronomy)
  • based on physics as well as mathematics
  • astronomer must explain why planets move as they do as well as describe how they move
Kepler on Elliptical Orbits

Why should I mince my words?  The truth of Nature, which I had rejected and chased away, returned by stealth through the backdoor, disguising itself to be accepted.  That is to say, I laid [the original equation] aside, and fell back on ellipses, believing that this was quite a different hypothesis, whereas the two ... are one and the same.

I thought and searched, until I went nearly mad, for a reason why the planet preferred an elliptical orbit [to mine]....

Ah, what a foolish bird I have been!

Kepler on Force that Controls Earth's Orbital Motion

It is therefore clear that the traditional doctrine about gravity is erroneous....

Gravity is the mutual bodily tendency between like bodies towards unity or contact (of which kind the magnetic force also is), so that the earth draws a stone much more than the stone draws the earth....

Suppose the earth were in the center of the world.  Heavy bodies would be attracted to it, not because it is in the center, but because it is a like body.  It follows that regardless where we place the earth ... heavy bodies will always seek it....

Notable Events in Kepler's Life (cont'd)

formulated "third law"--
T2/R3 = constant, for all satellites orbiting any given central body
published Harmonice Mundi (Harmony of the World)
  • synthesized geometry, music, astrology, astronomy
published Epitome Astronomiæ Copernicanæ (Epitome of Copernican Astronomy)
  • textbook guide to Kepler's system of the world 
published Rudolphine Tables

  • Kepler viewed himself as a "Copernican."  What did he mean by that?
  • Would you classify his work as "scientific"?

Go to:
  • Dialogue on the Two Chief World Systems (1632) by Galileo; and
Weekly Readings
Lecture Notes