Amongst those many Arguments that may bee urged for the confirmation of this truth, I shall set down only these five.
1 If we suppose the Earth to be the cause of this motion, then will those vast and glorious Bodies of the Heavens be freed from that inconceivable, unnaturall swiftnes, which must otherwise bee attributed unto them.
For if the diurnall revolution be in the Heavens,1 then it will follow according to the common Hypothesis, that each Starre in the Equator must in every houre move at the least 4529538 Germane miles. So that according to the observation of2 Cardan, who tels us, that the pulse of a well tempered man do’s beat 4000 times in an houre; one of these Starres in that space, whilst the pulse beats once, must passe 1132 Germane miles (saith Alphraganus:) Or according to Tycho 732 Germane miles. But these numbers seem to be somwhat of the least; and therefore many others doe much inlarge them, affirming that every Starre in the Equator, in one beating of the pulse, most move 2528 of these miles.
‘Tis the assertion of3 Calvius, that though the distance of the Orbs, and so consequently their swiftnesse, seeme to be altogether incredible; yet it is rather farre greater in it self, than Astronomers usually suppose it; & yet (saith he) according to the common grounds, every star in the Equator, must move 42398437½ miles in an houre. And though a man should constantly travel 40 miles a day; yet he would not be able to goe so far as a Star do’s in one houre, under 3904 yeares: Or if wee will suppose an Arrow to bee of the same swiftnesse, then must it compasse this great Globe of Earth and Water 1884 times in an hour. And a Bird that could but fly as fast, might go round the World seven times in that space, whilest one could say, Ave Maria, gratia plena, Dominus tecum.
Which though it be a pretty round pace; yet you must conceive that all this is spoken onely of the eighth Sphaere, and so being compared to the swiftnesse of the primum mobile, is but a slow and heavy motion.
For (saith the same author) the thicknesse of each Orbe is equall to the distance of it’s concave superficies from the centre of the Earth. Thus the Orbe of the Moone do’s containe as much space in it’s thicknesse, as there is betwixt the neerest parts of that and the centre. Thus also the eighth Sphaere is as thicke as that whole space betwixt the centre of the Earth, and it’s owne concave superficies. So likewise must it be in those three other Orbes, which he supposes to bee above the Starry Heaven. Now if we proportion their swiftnesse according to this difference in their bignesse, you may then conceive (if you can) what a kinde of celeritie that must be, by which the primum mobile wil be whirled about.
Tycho makes the distance of the Stars to bee much lesse, and their motion flower; and yet hee is faine to confesse, that it is omni cogitatione celerior.
Clavius likewise speaking concerning the swiftnesse of the Starry Orbe, do’s acknowledge, Quod velocitas ejus captum humani ingenij excedit. What then could he thinke of the primum mobile?
Dr Gilbert being (it seems) astonished at the consideration of this strange swiftnesse,4 sayes of it, that it is motus supra omnes cogitationes, somnia, fabulas & licentias poeticas insuperabilis, ineffabilis, incomprehensibilis. A man may more easily conceive the possibilitie of any Fable or Fiction how Beasts and Trees might talke together, than how any materiall Body should bee moved with such a swiftnesse.
Not but that ‘tis possible for God to turne them about with a farre greater velocitie. Nay ‘tis possible for Art to contrive a motion, which shall be equally slow in that proportion as this is swift. But however, the question here, is not what can be done, but what is most likely to be don according to the usuall course of Nature. ‘Tis the part of a Philosopher, in the resolution of naturall events, not to fly unto the absolute Power of God, and tell us what he can doe, but what according to the usuall way of Providence, is most likely to be done, to find out such causes of things, as may seem most easy & probable to our reason.
If you ask what repugnancy there is in the Heavens, unto so great a swiftnes: we answer, Their being such vast, materiall condensed substances, with which this inconceivable motion cannot agree.