Judicious Reader, There was published some years since in Rome a salutiferous edict which... imposed a seaonable silence upon the Pythagorean opinion of the mobility of the earth. ...that decree was not the production of sober scrutiny but of ill-informed passion... consultors altogether ignorant of astronomical observations ought not to clip the wings of speculative wits with rash prohibitions.
I thought fit... to appear openly upon the theatre of the World as a witness of the naked truth.
It is my resolution... to give foreign nations to see of this matter... And, collecting all the speculations of mine that concern the Copernican system, to let them know that... there proceed from this climate not only doctrines for the health of the soul but also ingenious discoveries for the delight of the mind.
I will endeavour to show that all experiments that can be made upon the Earth are insufficient means to conclude for its mobility but are indifferently applicable to the Earth, movable or immovable...
We will examine the celestial phenomena that make for the Copernican hypothesis, as if it were to prove absolutely victorious, adding by the way certain new observations which yet serve only for astronomical facility, not for natural necessity.
I will propose an ingenious fancy. ...the unknown problem of the tides might receive some light, admitting of the Earth's motion. ...I have thought good to lay down those probabilities that would render it credible, admitting that the Earth did move.
There had casually taken place... several discourses at times between these gentlemen which had rather inflamed than satisfied in their minds the thirst they had for learning; whereupon they took the wise resolution to meet together for certain days in which, all other business set aside, they might betake themselves with more ordered speculation to contemplate the wonders of God in heaven and on earth.
Nor need you question but that Pythagoras a long time be\xadfore he found the demonstration for which he offered the Hecatomb, had been certain, that the square of the side subtending the right angle in a rectangle triangle, was equal to the square of the other two sides: and the certainty of the conclusion condu\xadced not a little to the investigating of the demonstration, un\xadderstanding me alwayes to mean in demonstrative Sciences.
What ever was the method of Aristotle, and whether his arguing à priori preceded sense à posteriori, or the contrary; it sufficeth that the same Aristotle preferreth (as hath been oft said) sensible ex\xadperiments before all discourses...
If I was demanded what my first apprehension, and pure natural reason dictated to me concerning the production of things like or unlike there above, I would alwayes reply, that they are most different, and to us altogether unimaginable, for so me thinks the riches of Nature, and the omnipotence of our Creator and Governour, do require.
The having a perfect knowledg of nothing, maketh some believe they understand all things.
Your discourse is very concluding; in confirmation of which we have the example of those who understand, or have known some thing, which the more knowing they are, the more they know, and freely confesse that they know little; nay, the wisest man in all Greece, and for such pronounced by the Oracle, openly professed to know that he knew nothing.
It must be granted therefore, either that Socrates or that the Oracle itself was a lyar, that declaring him to be most wise, and he confessing that he knew himself to be most ig\xadnorant.
As to the truth, of which Mathematical demonstrations give us the knowledge, it is the same, which the divine wisdom knoweth; but this I must grant you, that the manner whereby God knoweth the infinite propo\xadsitions, of which we understand some few... his is done at one single thought or intuition; and whereas we... beginning from one of the most simple, and taking that for its definition, do proceed with argumentation to another...
What other, is that proposition, that the square of the side subtending the right angle in any triangle, is equal to the squares of the other two, which include it, but onely the Paralellograms being upon common bases, and between parallels equal amongst themselves?
These inferences, which our intellect apprehendeth with time and a gradual motion, the Divine Wisdom, like light, penetrateth in an instant, which is the same as to say, hath them alwayes pre\xadsent...
Our understanding, both as to the manner and the multitude of the things comprehended by us, is infinitely surpast by the Divine Wisdom; but yet I do not so vilifie it, as to repute it absolutely nothing; yea rather, when I consider how many and how great misteries men have understood, discovered, and contrived, I very plainly know and understand the mind of man to be one of the works, yea one of the most ex\xadcellent works of God.
Because it is more easie for a man to sculk under anothers shield than to shew himself openly, they tremble, and are affraid to stir one step from him; and rather than they will admit some alterations in the Heaven of Aristotle, they will impertinently de\xadny those they behold in the Heaven of Nature.
Therefore Simplicius, come either with arguments and demonstrations of your own, or of Aristotle, and bring us no more Texts and na\xadked authorities, for our disputes are about the Sensible World, and not one of Paper.
Whatsoever motion may be ascribed to the Earth, it is necessary that it be to us, (as inhabitants upon it, and conse\xadquently partakers of the same) altogether imperceptible, and as if it were not at all, so long as we have regard onely to terrestrial things...
If we consider onely the immense magnitude of the Starry Sphere, compared to the smalness of the Terrestrial Globe, contained therein so many mil\xadlions of times; and moreover weigh the velocity of the motion which must in a day and night make an entire revolution thereof, I cannot perswade my self, that there is any man who believes it more reasonable and credible, that the Cœlestial Sphere turneth round, and the Terrestrial Globe stands still.
He which should hold it more ra\xadtional to make the whole Universe move, and thereby to salve the Earths mobility, is more unreasonable than he that being got to the top of your Turret, should desire, to the end onely that he might behold the City, and the Fields about it, that the whole Country might turn round, that so he might not be put to the trouble to stir his head.
Nature never doth that by many things, which may be done by a few.
I would be loth to leave you in that other which you hold, namely, that a material Sphere doth not touch a plain in one sole point: and I could wish some few hours conversation with some persons conversant in Geometry, might make you a little more intelligent amongst those who know nothing thereof.
The truth sometimes gaines strength by con\xadtradiction.
Things are ex\xadactly the same in abstract as in con\xadcrete.
Contact in a sin\xadgle point is not pe\xadculiar to the per\xadfect Spheres onely, but belongeth to all curved figures.
It is more diffi\xadcult to find Figures that touch with a part of their sur\xadface, than in one sole point.
If any figure can be given to a Solid, the Spherical is the easi\xadest of all others, as it is likewise the most simple, and holdeth the same place amongst solid figures, as the Circle holdeth amongst the superficial. The description of which Circle, as being more ea\xadsie than all the rest, hath alone been judged by Mathematicians worthy to be put amongst the postulata belonging to the descri\xadption of all other figures.
The circular Fi\xadgure only is placed amongst the postu\xadlata of Mathema\xadticians.
The Sphericall Figure is easier to be made than any other. ...Sphericall Fi\xadgures of sundry magnitudes may be made with one onely instrument.
Nature first made things as she pleased, and after\xadwards capacitated mens understand\xadings for conceiving of them.
If I deny his [Aristotle's] assumption, to wit, that the Universe is moveable, all his demonstrations come to nothing, for he onely proveth the Universe to be finite and terminate, for [by assuming] that it is moveable.
I do not ask the Peripateticks... they, as observant and humble vassals of Aristotle, would deny all the ex\xadperiments and all the observations in the World, nay, would also refuse to see them, that they might not be forced to acknowledg them, and would say that the World stands as Aristotle writeth, and not as nature will have it, for depriving them of the shield of his Authority, with what do you think they would appear in the field?
Now if it were true that the centre of the World is the same about which... the Planets, move, it is most certain that it is not the Earth, but the Sun rather that is fixed in the centre of the World. So that as to this first simple and general apprehension, the middle place belongeth to the Sun, and the Earth is as far remote from the centre, as it is from that same Sun.
The seeing all the Planets one while neerer and ano\xadther while farther off from the Earth with so great differences, that for example, Venus when it is at the farthest, is six times more remote from us, than when it is neerest, and Mars riseth almost eight times as high at one time as at another.
The annual mo\xadtion of the Earth mixing with the motions of the o\xadther Planets pro\xadduce extravagant appearances.
As to the operation of the diurnal motion upon the Celestial bodies, it neither was, nor can be other, than to make the Universe seem to run precipitately the contrary way; but this annual motion intermixing with the particular motions of all the planets, produceth very many ex\xadtravagancies, which have disarmed and non-plust all the greatest Scholars in the World.
The centre of the Celestial conversions of the five planets Saturn, Jupiter, Mars, Venus and Mercury, is the Sun; and shall be likewise the centre of the motion of the Earth, if we do but succeed in our attempt of placing it in Hea\xadven.
Although Astronomy in the courses of many ages hath made a great progress in discovering the constitution and motions of the Celestial bodies, yet is it not hitherto arrived at that height, but that very many things remain undecided, and haply many others also undiscovered.
We have now, from these four dayes Dis\xadcourse, great attestations, in favour of the Copernican Systeme, amongst which these three taken: the first, from the Stations and Retrogradations of the Planets, and from their approaches and recessions from the Earth; the second, from the Suns revolving in it self, and from what is observed in its spots; the third, from the Ebbing and Flowing of the Sea do shew very rational and concluding.
And you Sagredus, although in the Discourses past you have many times, with great applause, declared, that you were pleased with some of my conjectures, yet do I believe, that that was in part more occasioned by the novelty than by the cer\xadtainty of them, but much more by your courtesie, which did think and desire, by its assent, to procure me that content which we naturally use to take in the approbation and applause of our own matters... your civility hath obliged me to you...
So am I also pleased with the ingenuity of Simplicius. Nay, his constancy in maintaining the Doctrine of his Master, with so much strength & undauntedness, hath made me much to love him. ...I ask pardon, if I have sometimes moved him with my too bold and resolute speaking: and let him be assured that I have not done the same out of any inducement of sinister affection, but onely to give him occasion to set before us more lofty fancies that might make me the more knowing.
Above all, I shall very impatiently wait to hear the Elements of the new Science of our Academick about the natural and violent local Motions. And in the mean time, we may, according to our custome, spend an hour in taking the Air in the Gondola that waiteth for us. FINIS.