TO HIS HOLINESS, POPE PAUL III,

D SANCTISSIMVM DOMINVM PAVLVM III. PONTIFICEM MAXIMVM,

NICHOLAS COPERNICUS' PREFACE TO HIS BOOKS ON THE REVOLUTIONS

Nicolai CoperniciPraefatio in libros | Reuolutionum.

I can readily imagine, Holy Father, that as soon as some people hear that in this volume, which I have written about the revolutions of the spheres of the universe, I ascribe certain motions to the terrestrial globe, they will shout that I must be immediately repudiated together with this belief For I am not so enamored of my own opinions that I disregard what others may think of them. I am aware that a philosopher's ideas are not subject to the judgement of ordinary persons, because it is his endeavor to seek the truth in all things, to the extent permitted to human reason by God. Yet I hold that completely erroneous views should be shunned. Those who know that the consensus of ἀκρόαμα many centuries has sanctioned the conception that the earth remains at rest in the middle of the heaven as its center would, I reflected, regard it as an insane pronouncement if I made the opposite assertion that the earth moves.

Satis equidem, Sanctissime Pater, aestimare possum, futurum esse, ut simul atque quidam acceperint, me hisce meis libris, quos de Reuolutionibus sphaerarum mundi scripsi, terrae globo tribuere quosdam motus, statim me explodendum cum tali opinione clamitent. Neque enim ita mihi mea placent, ut non perpendam, quid alii de illis iudicaturi sint. Et quamuis sciam, hominis philosophi cogitationes esse remotas a iudicio uulgi, propterea quod illius studium sit ueritatem omnibus in rebus, quatenus id a Deo rationi humanae permissum est, inquirere, tamen alienas prorsus a rectitudine opiniones fugiendas censeo. Itaque cum mecum ipse cogitarem, quam absurdum ἀκρόαμα eexistimaturi essent illi, qui multorum seculorum iudiciis hanc opinionem confirmatam norunt, quod terra immobilis in medio coeli, tanquam centrum illius posita sit, si ego contra assererem terram moueri,

Therefore I debated with myself for a long time whether to publish the volume which I wrote to prove the earth's motion or rather to follow the example of the Pythagoreans and certain others, who used to transmit philosophy's secrets only to kinsmen and friends, not in writing but by word of mouth, as is shown by Lysis' letter to Hipparchus. And they did so, it seems to me, not, as some suppose, because they were in some way jealous about their teachings, which would be spread around; on the contrary, they wanted the very beautiful thoughts attained by great men of deep devotion not to be ridiculed by those who are reluctant to exert themselves vigorously in any literary pursuit unless it is lucrative; or if they are stimulated to the nonacquisitive study of philosophy by the exhortation and example of others, yet because of their dullness of mind they play the same part among philosophers as drones among bees.

diu mecum haesi, an meos commentarios in eius motus demonstrationem conscriptos in lucem darem, an uero satius esset, Pythagoreorum et quorundam aliorum sequi exemplum, qui mon per literas, sed per manus tradere soliti sunt mysteria philosophiae propinquis et amicis duntaxat. Sicut Lysidis ad Hipparchum epistola testatur'). Ac mihi quidem uidentur id fecisse: non ut quidam arbitrantur ex quadam inuidentia communicandarum doctrinarum, Sed ne respulcherrimae, et multo studio magnorum uirorum imuestigatae, ab illis contemnerentur, quos aut piget ullis literis bonam operam impendere, misi quaestuosis, aut si exhortationibus et exemplo aliorum ad liberale studium philosophiae excitentur, tamen propter * stupiditatem ingenii inter philosophos, tanquam fuci inter apes uersantur.

When I weighed these considerations, the scorn which I had reason to fear on account of the novelty and unconventionality of my opinion almost induced me to abandon completely the work which I had undertaken. But while I hesitated for a long time and even resisted, my friends drew me back. Foremost among them was the cardinal of Capua, Nicholas Schönberg, renowned in every field of learning. Next to him was a man who loves me dearly, Tiedemann Giese, bishop of Chelmno, a close student of sacred letters as well as of all good literature. For he repeatedly encouraged me and, sometimes adding reproaches, urgently requested me to publish this volume and finally permit it to appear after being buried among my papers and lying concealed not merely until the ninth year but by now the fourth period of nine years. The same conduct was recommended to me by not a few other very eminent scholars. They exhorted me no longer to refuse, on account of the fear which I felt, to make my work available for the general use of students of astronomy.

Cum igitur haec mecum perpenderem, contemptus, qui mihi propter nouitatem et absurditatem opinionis metuendus erat, propemodum impulerat me, ut institutum opus prorsus intermitterem. Verum amici me diu cunctantem atque etiam reluctantem retraxerunt, inter quos primus fuit Nicolaus Schonbergius Cardinalis Capuanus, in omni genere doctrinarum celebris. Proximus illi uir mei amantissimus Tidemannus Gisius, Episcopus Culmensis, sacrarum ut est, et omnium bonarum literarum studiosissimus. Is etenim saepenumero me adhortatus est, et conuitiis interdum additis efflagitauit, ut librum hunc aederem, et in lucem tandem prodire sinerem, qui apud me pressus non in nonum annum solum*), sed iam in quartum mouennium, latitasset. Idem apud me egerunt alii mon pauci uiri eminentissimi et doctissimi, adhortantes ut meam operam ad communem studiosorum Mathematices utilitatem, propter conceptum metum, conferre non recusarem diutius.

The crazier my doctrine of the earth's motion now appeared to most people, the argument ran, so much the more admiration and thanks would it gain after they saw the publication of my writings dispel the fog of absurdity by most luminous proofs. Influenced therefore by these persuasive men and by this hope, in the end I allowed my friends to bring out an edition of the volume, as they had long besought me to do.

Fore ut quanto absurdior plaerisque nunc haec mea doctrina de terrae motu uideretur, tanto plus admirationis atque gratiae habitura esset, postquam per aeditionem commentariorum meorum caliginem absurditatis sublatam uiderent liquidissimis demonstrationibus. His igitur persuasoribus, eaque spe adductus, tandem amicis permisi, ut aeditionem operis, quam diu a me petissent, facerent.

However, Your Holiness will perhaps not be greatly surprised that I have dared to publish my studies after devoting so much effort to working them out that I did not hesitate to put down my thoughts about the earth's motion in written fcrm too. But you are rather waiting to hear from me how it occurred to me to venture to conceive any motion of the earth, against the traditional opinion of astronomers and almost against common sense. I have accordingly no desire to from Your Holiness that I was impelled to consider a different system of deducing the motions of the universe's spheres for no other reason than the realization that astronomers do not agree among themselves in their investigations of this subject.

At non tam mirabitur fortasse Sanctitas tua, quod has meas lucubrationes aedere in lucem ausus sim, posteaquam tantum operae in illis elaborandis, mihi sumpsi, ut meas cogitationes de terrae motu etiam literis committere mom dubitauerim, sed quod magis ex me audire expectat, qui mihi im mentem uemerit, ut contra receptam opinionem Mathematicorum, ac propemodum contra communem sensum, ausus fuerim imaginari aliquem motum terrae. Itaque nolo Sanctitatem tuam latere, me nihil aliud mouisse, ad cogitandum de alia ratione subducendorum motuum sphaerarum mundi, quam quod intellexi, Mathematicos sibi ipsis non constare in illis perquirendis.

For, in the first place, they are so uncertain about the motion of the sun and moon that they cannot establish and observe a constant length even for the tropical year. Secondly, in determining the motions not only of these bodies but also of the other five planets, they do not use the same principles, assumptions, and explanations of the apparent revolutions and motions. For while some employ only homocentrics, others utilize eccentrics and epicycles, and yet they do not quite reach their goal. For although those who put their faith in homocentrics showed that some nonuniform motions could be compounded in this way, nevertheless by this means they were unable to obtain any incontrovertible result in absolute agreement with the phenomena.

Primum enim usque adeo incerti sunt de motu Solis et Lunae, ut mec uertentis anni perpe*tuam magnitudinem demonstrare et obseruare possint. Deinde in comstituendis motibus, cum illarum, tum aliarum quinque errantium stellarum, neque iisdem principiis et assumptionibus, ac apparentium reuolutionum motuumque demonstrationibus, utuntur. Alii namque circulis homocentris solum, alii eccentris et epicyclis, quibus tamen quaesita ad plenum non assequuntur. Nam qui homocentris confisi sunt, etsi motus aliquos diuersos ex eis componi posse demonstrauerint, nihil tamen certi, quod nimirum phaenomenis responderet, inde statuere potuerunt.

On the other hand, those who devised the eccentrics seem thereby in large measure to have solved the problem of the apparent motions with appropriate calculations. But meanwhile they introduced a good many ideas which apparently contradict the first principles of uniform motion. Nor could they elicit or deduce from the eccentrics the principal consideration, that is, the structure of the universe and the true symmetry of its parts. On the contrary, their experience was just like some one taking from various places hands, feet, a head, and other pieces, very well depicted, it may be, but not for the representation of a single person; since these fragments would not belong to one another at all, a monster rather than a man would be put together from them. Hence in the process of demonstration or "method", as it is called, those who employed eccentrics are found either to have omitted something essential or to have admitted something extraneous and wholly irrelevant.

Qui uero excogitauerunt eccentrica, etsi magna ex parte apparentes motus congruentibus per ea numeris absoluisse uideantur: plaeraque tamen interim admiserunt, quae primis principiis, de motus aequalitate, uidentur contrauenire. Rem quoque praecipuam, hoc est mundi formam, ac partium eius certam symmetriam non potuerunt inuenire, vel ex illis colligere'). Sed accidit eis perinde, ac si quis e diuersis locis, manus, pedes, caput, aliaque membra, optime quidem, sed mon unius corporis comparatione, depicta sumeret, nullatenus inuicem sibi respondentibus, ut monstrum potius quam homo ex illis componeretur*). Itaque in processu demonstrationis, quam μέθοδον uocant, vel praeteriisse aliquid necessariorum vel alienum quid, et ad rem minime pertinens, admisisse inueniuntur. Id quod illis minime accidisset, si certa principia sequuti essent.

This would not have happened to them, had they followed sound principles. For if the hypotheses assumed by them were not false, everything which follows from their hypotheses would be confirmed beyond any doubt. Even though what I am now saying may be obscure, it will nevertheless become clearer in the proper place.

Nam si assumptae illorum hypotheses non essent fallaces, omnia quae ex illis sequuntur, uerificarentur procul dubio. Obscura autem licet haec sint, quae numc dico, tamen suo loco fient apertiora.

BOOK 1

CHAPTER 10