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Galileo Galilei to Benedetto Castelli


Very Reverend Father and My Most Respectable Sir

Yesterday Mr. Niccolò Arrighetti came to visit me and told me about you. Thus I took infinite pleasure in hearing about what I did not doubt at all, namely about the great satisfaction you have been giving to the whole University.. However, the seal of my pleasure was to hear him relate the arguments which through the great kindness of their Most Serene Highness, you had the occasion of advancing at their table and then of continuing in the chambers of the Most Serene Ladyship, in the presence also of the Grand Duke and the Most Serene Archduchess, the Most Illustrious and Excellent Don Antonio and Don Paolo Giordano, and some of the very excellent philosophers there. What greater fortune can you wish than to se their Highnesses themselves enjoying discussing with you, putting forth doubts, listening to your solutions, and finally remaining satisfied with your answers?

After Mr. Arrighetti related the details you had mentioned, they gave me the occasion to go back to examine some general questions about he use of the Holy Scripture in disputes involving physical conclusions and some particular other ones about Joshua’s passage, which was presented in opposition to the earth’s motion and sun’s stability by the Grand Duchess Dowager with some support by the Most Serene Archduchess.

In regard to the first general point of the Most Serene Ladyship, it seems to me very prudent of her to propose and of you to concede and to agree that the Holy Scripture can never lie or err, and that its declarations are absolutely and inviolably true. I should have added only that, through the Scripture cannot err, nevertheless some of its interpreters and expositors can sometimes err in various ways. One of these would be very serious and very frequent, namely to want to limit oneself always to the literal meaning of the words; for there would thus emerge not only various contradictions but also serious heresies and blasphemies, and it would be necessary to attribute to God feet, hands and eyes, as well as bodily and human feelings like anger, regret, hate and sometimes even forgetfulness of things past and ignorance of future ones. Thus in the Scripture one finds many propositions which look different from the truth if one goes by the literal meaning of the words, but which are expressed in this manner to accommodate the incapacity of common people; likewise, for the few who deserve to be separated from the masses, it is necessary that wise interpreters produce their true meaning and indicate the particular reasons why they have been expressed by means of such words.

Thus, given that in many places the Scripture is not only capable but necessarily in need of interpretations different from the apparent meaning of the words, it seems to me that in disputes about natural phenomena it should be reserved to the last place. For the Holy Scripture and nature both equally derive from the divine Word, the former as the dictation of the Holy Spirit, the latter as the most obedient executrix of God’s commands; moreover, in order to adapt itself to the understanding of all people, it was appropriate for the Scripture to say many things which are different from absolute truth, in appearance and in regard to the meaning of the words; on the other hand, nature is inexorable and immutable, and she does not care at all whether or not her recondite reasons and modes of operations are revealed to human understanding, and so she never transgresses the terms of the laws imposed on her; therefore, whatever sensory experience places before our eyes or necessary demonstrations prove to us concerning natural effects should not in any way be called into question on account of scriptural passages whose words appear to have a different meaning, since not every statement of the Scripture is bound to obligations as severely as each effect of nature. Indeed, because of the aim of adapting itself to the capacity of unrefined and undisciplined peoples, the Scripture has not abstained from somewhat concealing its most basic dogmas, thus attributing to God himself properties contrary to and very far from his essence; so who will categorically maintain that, in speaking even incidentally of the earth of the sun or other creatures, it abandoned this aim and chose to restrict itself rigorously within the limited and narrow meanings of the words: This would have been especially problematic when saying about these creatures things which are very far from the primary function of the Holy Writ, indeed things which, if said and put forth in their naked and unadorned truth, would more likely harm its primary intention and make people more resistant to persuasion about the articles pertaining to salvation.

Given this, and moreover it being obvious that two truths can never contradict each other, the task of wise interpreters is to strive to find the true meanings of scriptural passages agreeing with those physical conclusions of which we are already certain and sure from clear sensory experience or from necessary demonstrations. Furthermore, as I already said, though the Scripture was inspired by the Holy Spirit, because of the mentioned reasons many passages admit of interpretations far removed from the literal meaning, and also we cannot assert with certainty that all interpreters speak by divine inspiration; hence I should think it would be prudent not to allow anyone to oblige scriptural passages to have to maintain the truth of any physical conclusions whose contrary could ever be proved to us by the senses and demonstrative and necessary reasons. Who wants to fix a limit for the human mind? Who wants to assert that everything which is knowable in the world is already known? Because of this, it would be most advisable not to add anything beyond necessity to the articles concerning salvation and the definition of the Faith, which are firm enough that there is no danger of any valid and effective doctrine ever rising against them. If this is so, what greater disorder would result from adding them upon request by persons of whom we do not know whether they speak with celestial inspiration, and of whom also we see clearly that they are completely lacking in the intelligence needed to understand, let alone to criticize, the demonstrations by means of which the most exact sciences proceed in the confirmation of some of their conclusions?

I should believe that the authority of the Holy Write has merely the aim of persuading men of those article and propositions which are necessary for their salvation and surpass all human reason, and so could not become credible through some other science or any other means except the mouth of the Holy Spirit itself. However, I do not think it necessary to believe that the same God who has furnished us with senses, language, and intellect would want to bypass their use and give us by other means the information we can obtain with them. This applies especially to those sciences about which one can read only very small phrases and scattered conclusions in the Scripture, as is particularly the case for astronomy, of which it contains such a small portion that one does not even find in it the names of all the planets; but if the first sacred writers had been thinking of persuading the people about the arrangement and the movements of the heavenly bodies, they would not have treated of them so sparsely, which is to say almost nothing in comparison to the infinity of very lofty and admirable conclusions contained in such a science.

So you see, if I am not mistaken, how disorderly is the procedure of those who in disputes about natural phenomena that do not directly involve the Faith give first place to scriptural passages, which they quite often misunderstand anyway. However, if these people really believe they have grasped the true meaning of a particular scriptural passage, and if they consequently feel sure of possessing the absolute truth on the question they intend to dispute about, then let them sincerely tell me whether they think that someone in a scientific dispute who happens to be right has a great advantage over another who happens to be wrong. I know they will answer Yes, and that the one who supports the true side will be able to provide a thousand experiments and a thousand necessary demonstrations for his side, whereas the other person can have nothing but sophisms, paralogisms, and fallacies. But is they know they have such an advantage over their opponents as long as the discussion is limited to physical questions and only philosophical weapons are used, why is it that when they come to the meeting they immediately introduce an irresistible and terrible weapon, the mere sight of which terrifies even the most skillful and expert champion? If I must tell the truth, I believe it is they who are the most terrified, and that they are trying to find a way of not letting the opponent approach because they feel unable to resist his assaults. However, consider that, as I just said, whoever has truth on his side has a great, indeed the greatest, advantage over the opponent, and that it is impossible for two truths to contradict each other; it follows therefore that we must not fear any assaults launched against us by anyone, as long as we are allowed to speak and to be heard by competent persons who are not excessively upset by their own emotions and interests.\

To confirm this I now come to examining the specific passage of Joshua, concerning which you put forth three theses for their Most Serene Highness. I take the third one, which you advanced as mine (as indeed it is), but I add some other consideration that I do not believe I have ever told you.

Let us then assume and concede to the opponent that the words of the sacred text should be taken precisely in their literal meaning, namely that in answer to Joshua’s prayers God made the sun stop and lengthened the day, so that as a result he achieved victory; but I request that the same rule should apply to both, so that the opponent should not pretend to tie me and to leave himself free to change or modify the meanings of the words. Given this, I say that this passage shows clearly the falsity and impossibility of the Aristotelian and Ptolemaic world system, and on the other hand agrees very well with the Copernican one.

I first ask the opponent whether he knows with how many motions the sun moves. If he knows, he must answer that is moves with two motions, namely with the annual motion from west to east and with the diurnal motion in the opposite direction from east to west.

Then, secondly, I ask him whether these two motions, so different and almost contrary to each other, belong to the sun and are its own to an equal extent. The answer must be No, but that only one is specifically its own, namely the annual motion, whereas the other is not but belongs to the highest heaven, I mean the Prime Mobile; the latter carries along with it the sun as well as the other planets and the stellar sphere, forcing them to make a revolution around the earth in twenty-four hours, with a motion, as I said, almost contrary to their own natural motion.

Coming to the third question, I ask him with which of these two motions the sun produces night and day, that is, whether with its own motion or else with that of the Prime Mobile. The answer must be that night and day are effects of the motion of the Prime Mobile and that what depends on the sun’s own motion is not night or day but the various seasons and the year itself.

Now, if the day derives not from the sun’s motion but from that of the Prime Mobile, who does not see that to lengthen the day one must stop the Prime Mobile and not the sun? Indeed, is there anyone who understands these first elements of astronomy and does not know that, if God had stopped the sun’s motion, He would have cut and shortened the day instead fo lengthening it? For, the sun’s motion being contrary to the diurnal turning, the more the sun moves toward the east the more its progression toward the west is slowed down, whereas by its motion being diminished or annihilated the sun would set that much sooner; this phenomenon is observed in the moon, whose diurnal revolutions are slower than those of the sun inasmuch as is own motion is faster than that of the sun. It follows that it is absolutely impossible to stop the sun and lengthen the day in the system of Ptolemy and Aristotle, and therefore either the motions must not be arranged as Ptolemy says or we must modify the meaning of the words of the Scripture; we would have to claim that, when it says that God stopped the sun, it meant to say that He stopped the Prime Mobile, and that is said the contrary of what it would have said if speaking to educated men in order to adapt itself to the capacity of those who are barely able to understand the rising and setting of the sun.

Add to this that it is not believable that God would stop only the sun, letting the other spheres proceed; for He would have unnecessarily altered and upset all the order, appearances, and arrangements of the other stars in relation to the sun, and would have greatly disturbed the whole system of nature. On the other hand, it is believable that He would stop the whole system of celestial spheres, which could then together return to their operations without any confusion or change after the period of intervening rest.

However, we have already agreed not to change the meaning of the words in the text; therefore it is necessary to resort to another arrangement of the parts of the world, and to see whether the literal meaning of the words flows directly and without obstacle from its point of view. This is in fact what we see happening.

For I have discovered and conclusively demonstrated that the solar globe turns on itself, completing an entire rotation in about one lunar month, in exactly the same direction as all the other heavenly revolutions; moreover, it is very probable and reasonable that, as the chief instrument and minister of nature and almost the heart of the world, the sun gives not only light (as it obviously does) but also motion to all the planets that revolve around it; hence, if in conformity with Copernicus’s position the diurnal motion is attributed to the earth, anyone can see that is sufficed stopping the sun to stop the whole system, and thus to lengthen the period of the diurnal illumination without altering in any way the rest of the mutual relationships of the planets; and that is exactly how the words of the sacred text sound. Here then is the manner in which by stopping the sun one can lengthen the day on the earth, without introducing any confusion among the parts of the world and without altering the words of the Scripture.

I have written much more than is appropriate in the view of my slight illness. So I end by reminding you that I am at your service, and I kiss your hands and pray the Lord to give you happy holidays and all you desire.

Florence, December, 21, 1613

To Your Very Reverend Paternity.

Your Most Affectionate Servant, Galileo Galilei

Original text published in Opere di Galileo Galilei , Edizione Nazionale edited by Antonio Favaro,  vol. V (Firenze: Giunti Barbera, 1968),  pp. 282-288.

William Shakespeare on this Bittersweet Life


No more be grieved at that which thou hast done:
Roses have thorns, and silver fountains mud;
Clouds and eclipses stain both moon and sun,
And loathsome canker lives in sweetest bud.
All men make faults, and even I in this,
Authorizing thy trespass with compare,
Myself corrupting, salving thy amiss,
Excusing thy sins more than thy sins are;
For to thy sensual fault I bring in sense–
Thy adverse party is thy advocate–
And ‘gainst myself a lawful plea commence:
Such civil war is in my love and hate
That I an accessory needs must be
To that sweet thief which sourly robs from me.

John Calvin on Striving for Understanding Beyond Biblical Revelation


There are others who, when they would cure this disease, recommend that the subject of predestination should scarcely if ever be mentioned, and tell us to shun every question concerning it as we would a rock. Although their moderation is justly commendable in thinking that such mysteries should be treated with moderation, yet because they keep too far within the proper measure, they have little influence over the human mind, which does not readily allow itself to be curbed. Therefore, in order to keep the legitimate course in this matter, we must return to the word of God, in which we are furnished with the right rule of understanding. For Scripture is the school of the Holy Spirit, in which as nothing useful and necessary to be known has been omitted, so nothing is taught but what it is of importance to know. Every thing, therefore delivered in Scripture on the subject of predestination, we must beware of keeping from the faithful, lest we seem either maliciously to deprive them of the blessing of God, or to accuse and scoff at the Spirit, as having divulged what ought on any account to be suppressed. Let us, I say, allow the Christian to unlock his mind and ears to all the words of God which are addressed to him, provided he do it with this moderation viz. that whenever the Lord shuts his sacred mouth, he also desists from inquiry. The best rule of sobriety is, not only in learning to follow wherever God leads, but also when he makes an end of teaching, to cease also from wishing to be wise.


Nicolaus Copernicus on Philosophical Precedents for Heliocentrism


For a long time, then, I reflected on this confusion in the astronomical traditions concerning the derivation of the motions of the universe’s spheres. I began to be annoyed that the movements of the world machine, created for our sake by the best and most systematic Artisan of all, were not understood with greater certainty by the philosophers, who otherwise examined so precisely the most insignificant trifles of this world. For this reason I undertook the task of rereading the works of all the philosophers which I could obtain to learn whether anyone had ever proposed other motions of the universe’s spheres than those expounded by the teachers of astronomy in the schools. And in fact first I found in Cicero that Hicetas supposed the earth to move. Later I also discovered in Plutarch that certain others were of this opinion. I have decided to set his words down here, so that they may be available to everyone: “Some think that the eart remains at rest. But Philolaus the Pythagorean believes that, like the sun and moon, it revolves around the fire in an oblique circle. Heraclides of Pontus and Exphantus the Pythagorean make the earth move, not in a progressive motion, but like a wheel in a rotation from the west to east about its own center.”

John Calvin on Revelation


For how can the human mind measure off the measureless essence of God according to its own little measure, a mind as yet unable to establish for certain the nature of the sun’s body, though men’s eyes daily gaze upon it? Let us then willingly leave to God the knowledge of himself … But we shall be “leaving it to him” if we conceive him to be as he reveals himself to us, without inquiring about him elsewhere than from his Word.


Anselm of Canterbury on Forgiveness


Of forgiveness, indeed, I speak briefly, for, as we said above, vengeance in no sense belongs to you, since you are not your own, nor is he who injures you yours or his, but you are both the servants of one Lord, made by him out of nothing. And if you avenge yourself upon your fellow servant, you proudly assume judgment over him when it is the peculiar right of God, the judge of all. But what do you give to God by your obedience, which is not owed him already, since he demands from you all that you are and have and can become?

Anselm on Discernment


The intelligent creature received the power of discernment for this purpose, that he might hate and shun evil, and love and choose good, and especially the greater good. For else in vain would God have given him that power of discernment, since man’s discretion would be useless unless he loved and avoided according to it.

Anselm of Canterbury on Scripture


That the Bible is God’s Word and book I prove thus: All things that have been, and are, in the world, and the manner of their being, are described in the first book of Moses on the creation; even as God made and shaped the world, so does it stand to this day. Infinite potentates have raged against this book, and sought to destroy and uproot it — king Alexander the Great, the princes of Egypt and of Babylon, the monarchs of Persia, of Greece, and of Rome, the emperors Julius and Augustus – but they nothing prevailed; they are all gone and vanished, while the book remains, and will remain for ever and ever, perfect and entire, as it was declared at first. Who has thus helped it — who has thus protected it against such mighty forces? No one, surely, but God himself, who is the master of all things. And `tis no small miracle how God has so long preserved and protected this book; for the devil and the world are sore foes to it. I believe that the devil has destroyed many good books of the church, as, aforetime, he killed and crushed many holy persons, the memory of whom has now passed away; but the Bible he was fain to leave subsisting.

Anselm of Canterbury on Divine Command Theory


When it is said that what God wishes is just, and that what He does not wish is unjust, we must not understand that if God wished anything improper it would be just, simply because he wished it. For if God wishes to lie, we must not conclude that it is right to lie, but rather that he is not God. For no will can ever wish to lie, unless truth in it is impaired, nay, unless the will itself be impaired by forsaking truth. When, then, it is said: “If God wishes to lie,” the meaning is simply this: “If the nature of God is such as that he wishes to lie;” and, therefore, it does not follow that falsehood is right, except it be understood in the same manner as when we speak of two impossible things: “If this be true, then that follows; because neither this nor that is true;” as if a man should say: “Supposing water to be dry, and fire to be moist;” for neither is the case. Therefore, with regard to these things, to speak the whole truth: If God desires a thing, it is right that he should desire that which involves no unfitness. For if God chooses that it should rain, it is right that it should rain; and if he desires that any man should die, then is it right that he should die. Wherefore, if it be not fitting for God to do anything unjustly, or out of course, it does not belong to his liberty or compassion or will to let the sinner go unpunished who makes no return to God of what the sinner has