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How to read the Bible in the light of the New Astronomical Discoveries


Astronomia Nova

In 1609, Johannes Kepler (1571-1630) publishes his Astronomia Nova. It is the same year in which Galileo Galilei points a telescope to the sky and publishes his Sidereus Nuncius. However, while Galileo’s observations and drawings reported on Sidereus Nuncius have no direct relation with the proposal of a heliocentric system, Kepler’s work suggests the first two laws of planetary motion, namely: 1) the planets move along elliptical orbits with the sun occupying one of the two foci; 2) the planets sweep equal areas in equal times. The third law of planetary motion, called “Harmonic Law,” which relates the orbital period of a planet to its mean distance from the Sun, will be published in1619.

In the Introduction, after mentioning important concepts in mechanics that would pave the way for a physical, not just a geometric view, of the solar system, Kepler adds a small treatise on biblical exegesis, by which he intended to harmonize Copernicanism with the statements of sacred Scripture, an issue that was already beginning to become important even among Protestant Reformers in Germany. The text we offer here is the central part of this short treatise.

Now the holy scriptures, too, when treating common things (concerning which it is not their purpose to instruct humanity), speak with humans in the human manner, in order to be understood by humans. The scriptures make use of what is generally acknowledged among humans, in order to weave in other things more lofty and divine.

No wonder, then, if Scripture also speaks in accordance with human perception when the truth of things is at odds with the senses, whether or not humans are aware of this. Who is unaware that the allusion in Psalm 19 is poetical? Here, under the image of the sun, are sung the spreading of the Gospel and even the sojourn of Christ the Lord in this world on our behalf; and in the singing the sun is said to emerge from the tabernacle of the horizon like a bridegroom from his marriage bed, exuberant as a strong man for the race. Which Virgil imitates thus:

Aurora leaving Tithonus's saffron-colored bed.[1]

(The Hebrew poetry was, of course, earlier.)

Astronomia Nova's original title page
Astronomia Nova's original title page

The psalmodist was aware that the sun does not go forth from the horizon as from a tabernacle (even though it may appear so to the eyes). On the other hand, he considered the sun to move for the precise reason that it appears so to the eyes. In either case, he expresses it so because in either case it appeared so to the eyes. He should not be judged to speak falsely in either case, for the perception of the eyes also has its truth, well suited to the psalmodist's more hidden aim, the adumbration of the Gospel and also of the Son of God. Likewise, Joshua [Joshua 10:12 ff.] makes mention of the valleys against which the sun and moon moved, because when he was at the Jordan it appeared so to him. Yet each writer was in perfect control of his meaning. David (and Syracides with him) was describing the magnificence of God made manifest, which he expressed so as to exhibit them to the eyes, and possibly also for the sake of a mystical sense spelled out through these visible things. Joshua meant that the sun be held back in its place in the middle of the sky for an entire day with respect to the sense of his eyes, since for other people during the same interval of time it would remain beneath the earth.

But thoughtless persons pay attention only to the verbal contradiction, "the sun stood still" versus "the earth stood still," not considering that this contradiction can only arise in an optical and astronomical context, and does not carry over into common usage. Nor are these thoughtless ones willing to see that Joshua was simply praying that the mountains not remove the sunlight from him, which prayer he expressed in words conforming to the sense of sight, as it would have been quite inappropriate to think, at that moment, of astronomy and of visual errors. For if someone had admonished him that the sun doesn't really move against the valley of Ajalon, but only appears to do so, wouldn't Joshua have exclaimed that he only asked for the day to be lengthened, however that might be done? He would therefore have replied in the same way if anyone had filed a lawsuit against him about the sun's perpetual rest and the earth's motion.

Now God easily understood from Joshua's words what he meant, and proved it by stopping the motion of the earth, so that the sun might appear to him to stop. For the gist of ]oshua's petition comes to this, that it might appear so to him, whatever the reality might meanwhile be. Indeed, that this appearance should come about was not vain and purposeless, but quite conjoined with the desired effect.

But see chapter 10 of the Astronomiae pars optica[2], where you will find reasons why, to absolutely everyone, the sun appears to move and not the earth: it is because the sun appears small and the earth large, and also because, owing to its apparent slowness, the sun's motion is perceived, not by sight, but by reasoning alone, through its changed proximity to the mountains over a period of time. It is therefore impossible for a previously uninformed reason to imagine anything but that the earth, along with the arch of heaven set over it, is like a great house, immobile, in which the sun, so small in stature, travels from one side to the other like a bird flying in the air.

What all people indeed imagine, gave the first line of holy scripture. "In the beginning," says Moses, "God created the heaven and the earth," because it is these two parts that chiefly present themselves to the sense of sight. It is as though Moses were to say to man, "This whole worldly edifice that you see, light above and dark and widely spread out below, upon which you are standing and by which you are roofed over, has been created by God."

Kepler's original woodcut fot Chapter 24
Kepler's original woodcut fot Chapter 24

In another passage [Jeremiah 37:37.], Man is asked whether he has learned how to seek out the height of heaven above, or the depths of the earth below, because to the ordinary man both appear to extend through equally infinite spaces. Nevertheless, there is no one in his right mind who, upon hearing these words, would use them to limit astronomers' diligence either in showing the contemptible smallness of the earth in comparison with the heavens, or in investigating astronomical distances. For these words do not concern measurement arrived at by reasoning. Rather, they concern physical measurement, which is utterly impossible for the human body, fixed upon the land and drawing upon the free air. Read all of Chapter 38 of Job, and compare it with matters discussed in astronomy and in physics.

Suppose someone were to assert, from Psalm 24, that the earth is founded upon rivers, in order to support the novel and absurd philosophical conclusion that the earth floats upon rivers. Would it not be correct to say to him that he should regard the Holy Spirit as a divine messenger and refrain from wantonly dragging Him into physics class? For in that passage the psalmodist intends nothing but what men already know and experience daily, namely, that the land, raised on high after the separation of the waters, has great rivers flowing through it and seas surrounding it. Not surprisingly, the same figure of speech is adopted in another passage, where the Israelites sing that they were seated upon the waters of Babylon [Psalm 737], that is, by the riverside, or on the banks of the Euphrates and Tigris.

If anyone easily accepts this, why can he not also accept that in other passages usually cited in opposition to the earth's motion we should likewise turn our eyes from physics to the aims of scripture?

A generation passes away (says Ecclesiastes [1:4]), and a generation comes, but the earth stands forever. Does it seem here as if Solomon wanted to argue with the astronomers? No; rather, he wanted to warn people of their own mutability, while the earth, home of the human race, remains always the same, the motion of the sun perpetually returns to the same place, the wind blows in a circle and returns to its starting point, rivers flow from their sources into the sea, and from the sea return to their sources, and finally, as these people perish, others are born. Life's tale is ever the same; there is nothing new under the sun.

You do not hear any physical dogma here. The message is a moral one, concerning something self-evident and seen by all eyes but little pondered. Solomon therefore urges us to ponder. Who is unaware that the earth is always the same? Who does not see the sun rise again daily from the east, rivers perennially flowing towards the sea, the winds returning in regular alternation, and men succeeding one another? But who really considers that the same drama of life is always being played, only with different characters, and that not a single thing in human affairs is new? So Solomon, by mentioning what is evident to all, warns of that which almost everyone wrongly neglects.

It is said, however, that Psalm 104, in its entirety, is a physical discussion, since the whole of it is concerned with physical matters. And in it, God is said to have "founded the earth upon its stability, that it not be laid low unto the ages of ages." But in fact, the psalmodist is very far from speculating about physical causes. For he entirely finds comfort in the greatness of God, who made all these things: he has composed a hymn to God the creator, in which he treats the world in order, as it appears to the eyes.

If you consider carefully, you will see that it is a commentary upon the six days of creation in Genesis. For in the latter the first three days are given to the separation of the regions: first, the region of light from the exterior darkness; second, the waters from the waters by the interposition of an extended region; and third, the land from the seas, where the earth is clothed with plants and shrubs. The last three days, on the other hand, are devoted to the filling of the regions so distinguished: the fourth, of the heavens; the fifth, of the seas and the air; and the sixth, of the land. And in this psalm there are likewise the same number of distinct parts, analogous to the works of the six days.

In the second verse, he enfolds the Creator with the vestment of light, first of created things, and the work of the first day.

The second part begins with the third verse, and concerns the waters above the heavens, the extended region of the heavens, and atmospheric phenomena that the psalmodist ascribes to the waters above the heavens, namely, clouds, winds, tornadoes, and lightning.

The third part begins with the sixth verse, and celebrates the earth as the foundation of the things being considered. The psalmodist relates everything to the earth and to the things that live on it, because, in the judgement of sight, the chief parts of the world are two: heaven and earth. He therefore considers that for so many ages now the earth has neither sunk nor cracked apart nor tumbled down, yet no one has certain knowledge of what it is founded upon.

He does not wish to teach things of which men are ignorant, but to recall to mind something they neglect, namely, God's greatness and potency in a creation of such magnitude, so solid and stable. If an astronomer teaches that the earth is carried through the heavens, he is not overturning what the psalmodist says here, nor is he subverting human experience. For it is still true that the land, the work of God the architect, has not toppled as our buildings usually do, consumed by age and rot; that it has not slumped to one side; that the dwelling places of living thing have not been set in disarray; that the mountains and coasts have stood firm, unmoved against the blast of wind and wave, as they were from the beginning. And then the psalmodist adds a beautiful sketch of the separation of the waters from the continents, and adorns his account by adding springs and the benefits that springs and crags provide for bird and beast. He also does not fail to mention the adorning of the earth's surface, included by Moses among the works of the third day, although the psalmodist derives it from its prior cause, namely, a humidification arising in the heavens, and embellishes his account by bringing to mind the benefits accruing from that adornment for the nurture and pleasure of humans and for the lairs of the beasts.

The fourth part begins with verse 20, and celebrates the work of the fourth day, the sun and the moon, but chiefly the benefit that the division of times brings to humans and other living things. It is this benefit that is his subject matter: it is clear that he is not playing the part of an astronomer here.

If he were, he would not fail to mention the five planets, than whose motion nothing is more admirable, nothing more beautiful, and nothing a better witness to the Creator's wisdom, for those who take note of it.

The fifth part, in verse 26, concerns the work of the fifth day, where he fills the sea with fish and ornaments it with sea voyages.

The sixth is added, rather obscurely, in verse 28, and concerns the animals living on land, created on the sixth day. At the end, in conclusion, he in general declares the goodness of God in sustaining all things and creating new things. So everything the psalmodist said of the world relates to living things. He tells nothing that is not generally acknowledged, because his purpose was to praise things that are known, not to seek out the unknown. It was his wish to invite men to consider the benefits accruing to them from these works of each of the days.

I, too, implore my reader, when he returns from the temple and enters astronomical studies, not to forget the divine goodness conferred upon men, to the consideration of which the psalmodist chiefly invites. I implore that, with me, he praise and celebrate the Creator's wisdom and greatness, which I unfold for him in the more perspicacious explanation of the world’s form, the investigation of causes, and the detection of errors of vision. Let him thus not only extol the safety of the living things of all of Nature in the firmness and stability of the earth, as a gift of God, but also acknowledge His wisdom expressed in its motion, at once so well hidden and so admirable.

But whoever is too stupid to understand astronomical science, or too weak to believe Copernicus without affecting his faith, I advise him that, having dismissed astronomical studies and having damned whatever philosophical opinions he pleases, he mind his own business and betake himself home to scratch in his own dirt patch, abandoning this wandering about the world. He should raise his eyes (his only means of vision) to this visible heaven and with his whole heart burst forth in giving thanks and praising God the creator. He can be sure that he worships God no less than the astronomer, to whom God has granted this, that with the mind's eye he see more penetratingly, and that he himself is able and willing to celebrate his God above whatever he discovers.

[1] Aeneid IV. 585.

[2] Kepler, Optics, Ch. 10, eng. tr. pp. 335-346.


Johannes Kepler, Astronomia Nova, engl. tr. by William H. Donahue (Santa Fe, New Mexico: Green Lion Press, 2020), pp. 29-33.