On the magnetick diurnal revolution of the Earth's
globe, as a probable assertion against the time-honoured
_opinion of a Primum Mobile_.
Among the ancients Heraclides of Pontus and Ecphantus, afterwards the
Pythagoreans, as Nicetas of Syracuse and Aristarchus of Samos, and some
others (as it seems), used to think that the earth moves, and that the
stars set by the interposition of the earth and rose by her retirement. In
fact they set the earth moving and make her revolve around her axis from
west to east, like a wheel turning on its axle. Philolaus the
Pythagorean[242] would have the earth to be one of the stars, and believed
that it turned in an oblique circle around fire, just as the sun and moon
have their own courses. He was a distinguished mathematician, and a most
able investigator of nature. But after Philosophy became a subject treated
of by very many and was popularized, theories adapted to the vulgar
intelligence or based on sophistical subtility occupied the minds of most
men, and prevailed like a torrent, the multitude consenting. Thereupon many
valuable discoveries of the ancients were rejected, and were dismissed to
perish in banishment; or at least by not being further cultivated and
developed became obsolete. So that Copernicus[243] (among later
discoverers, a man most deserving of literary honour) is the first who
attempted to illustrate the [Greek: phainomena] of {215} moving bodies by
new hypotheses: and these demonstrations of reasons others either follow or
observe in order that they may more surely discover the phænomenal harmony
of the movements; being men of the highest attainments in every kind of
learning. Thus supposed and imaginary orbs of Ptolemy and others for
finding the times and periods of the motions are not necessarily to be
admitted to the physical inquiries of philosophers. It is then an ancient
opinion and one that has come down from old times, but is now augmented by
important considerations that the whole earth rotates with a daily
revolution in the space of 24 hours. Well then, since we see the Sun and
Moon and other planets and the glory of all the stars approach and retire
within the space of one natural day, either the Earth herself must needs be
set in motion with a diurnal movement from West to East, or the whole
heaven and the rest of nature from East to West. But, in the first place,
it is not likely that the highest heaven and all those visible splendours
of the fixed stars are impelled along that most rapid and useless course.
Besides, who is the Master who has ever made out that the stars which we
call fixed are in one and the same sphere, or has established by reasoning
that there are any real and, as it were, adamantine sphæres? No one has
ever proved this as a fact; nor is there a doubt but that just as the
planets are at unequal distances from the earth, [244]so are those vast and
multitudinous lights separated from the Earth by varying and very remote
altitudes; they are not set in any sphærick frame or firmament (as is
feigned), nor in any vaulted body: accordingly the intervals of some are
from their unfathomable distance matter of opinion rather than of
verification; others do much exceed them and are very far remote, and these
being located in the heaven at varying distances, either in the thinnest
æther or in that most subtile quintessence, or in the void: how are they to
remain in their position during such a mighty swirl of the vast orbe of
such uncertain substance. There have been observed by astronomers 1022
stars; besides these, numberless others are visible, some indeed faint to
our senses, in the case of others our sense is dim and they are hardly
perceived and only by exceptionally keen eyes, and there is no one gifted
with excellent sight who does not when the Moon is dark and the air at its
rarest, discern numbers and numbers dim and wavering with minute lights on
account of the great distance: hence it is credible both that these are
many and that they are never all included in any range of vision. How
immeasurable then must be the space which stretches to those remotest of
fixed stars! How vast and immense the depth of that imaginary sphere! How
far removed from the Earth must the most widely separated stars be and at a
distance transcending all sight, all skill and thought! How monstrous then
such a motion {216} would be! It is evident then that all the heavenly
bodies set as if in destined places are there formed into sphæres, that
they tend to their own centres, and that round them there is a confluence
of all their parts. And if they have motion, that motion will rather be
that of each round its own centre, as that of the Earth is; or a forward
movement of the centre in an orbit, as that of the Moon: there would not be
circular motion in the case of a too numerous and scattered flock. Of these
stars some situate near the Æquator would seem to be borne around at a very
rapid rate, others nearer the pole to have a somewhat gentler motion,
others, apparently motionless, to have a slight rotation. Yet no
differences in point of light, mass or colours are apparent to us: for they
are as brilliant, clear, glittering and duskish toward the poles, as they
are near the Æquator and the Zodiack: those which remain set in those
positions do not hang, and are neither fixed, nor bound to anything of the
nature of a vault. All the more insane were the circumvolution of that
fictitious _Primum Mobile_, which is higher, deeper, and still more
immeasurable. Moreover, this inconceivable _Primum Mobile_ ought to be
material and of enormous depth, far surpassing all inferior nature in size:
for nohow else could it conduct from East to West so many and such vast
bodies of stars, and the universe even down to the Earth: and it requires
us to accept in the government of the stars a universal power and a
despotism perpetual and intensely irksome. That _Primum Mobile_ bears no
visible body, is nohow recognizable, is a fiction believed in by those
people, accepted by the weak-minded folk, who wonder more at our
terrestrial mass than at bodies so vast, so inconceivable, and so far
separated from us. But there can be no movement of infinity and of an
infinite body, and therefore no diurnal revolution of that vastest _Primum
Mobile_. The Moon being neighbour to the Earth revolves in 27 days; Mercury
and Venus have their own moderately slow motions; Mars finishes a period in
two years, Jupiter in twelve years, Saturn in thirty. And those also who
ascribe a motion to the fixed stars make out that it is completed in 36,000
years, according to Ptolemy, in 25,816 years, according to Copernicus'
observations; so that the motion and the completion of the journey always
become slower in the case of the greater circles. And would there then be a
diurnal motion of that _Primum Mobile_ which is so great and beyond them
all immense and profound? 'Tis indeed a superstition and in the view of
philosophy a fable now only to be believed by idiots, deserving more than
ridicule from the learned: and yet in former ages, that motion, under the
pressure of an importunate mob of philosophizers, was actually accepted as
a basis of computations and of motions, by mathematicians. The motions of
the bodies (namely planets) seem to take place eastward and following the
order of the signs. {217} The common run of mathematicians and philosophers
also suppose that the fixed stars in the same manner advance with a very
slow motion: and from ignorance of the truth they are forced to join to
them a ninth sphære. Whereas now this first and unthinkable _Primum
Mobile_, a fiction not comprehended by any judgment, not evidenced by any
visible constellation, but devised of imagination only and mathematical
hypothesis, unfortunately accepted and believed by philosophers, extended
into the heaven and beyond all the stars, must needs with a contrary
impulse turn about from East to West, in opposition to the inclination of
all the rest of the Universe. Whatsoever in nature is moved naturally, the
same is set in motion both by its own forces and by the consentient compact
of other bodies. Such is the motion of parts to their whole, of all
interdependent sphæres and stars in the universe: such is the circular
impulse in the bodies of the planets, when they affect and incite one
another's courses. But with regard to the _Primum Mobile_ and its contrary
and exceeding rapid movement, what are the bodies which incite it or propel
it? What is the nature that conspires with it? Or what is that mad force
beyond the _Primum Mobile_? Since it is in bodies themselves that acting
force resides, not in spaces or intervals. But he who thinks that those
bodies are at leisure and keeping holiday, while all the virtue of the
universe appertains to the very orbits and sphæres, is on this point not
less mad than he who, in some one else's house, thinks that the walls and
floors and roof rule the family rather than the wife and thoughtful
paterfamilias. Therefore not by the firmament are they borne along, or are
moved, or have their position; much less are those confused crowds of stars
whirled around by the _Primum Mobile_, nor are they torn away and huddled
along by a contrary and extremely rapid movement. Ptolemy of Alexandria
seems to be too timid and weak-minded in dreading the dissolution of this
nether world, were the Earth to be moved round in a circle. Why does he not
fear the ruin of the Universe, dissolution, confusion, conflagration, and
infinite disasters celestial and super-celestial, from a motion
transcending all thoughts, dreams, fables, and poetic licences,
insurmountable, ineffable, and inconceivable? Wherefore we are carried
along by a diurnal rotation of the earth (a motion for sure more
congruous), and as a boat moves above the waters, so do we turn about with
the earth, and yet seem to ourselves to be stationary, and at rest. Great
and incredible it seems to some philosophers, by reason of inveterate
prejudice, that the Earth's vast body should be swirled wholly round in the
space of 24 hours. But it would be more incredible that the Moon should
travel through her orbit, or complete an entire course in a space of 24
hours; more so the Sun or Mars; still more Jupiter and Saturn; more than
marvellous would be the velocity in the case of the {218} fixed stars and
the firmament; what in the world they would have to wonder at in the case
of their ninth sphere, let them imagine as they like. But to feign a
_Primum Mobile_ and to attribute to the thing thus feigned a motion to be
completed in the space of 24 hours, and not to allow this motion to the
Earth in the same interval of time, is absurd. For a great circle of the
Earth is to the ambit of the _Primum Mobile_ less than a furlong to the
whole Earth. If the diurnal rotation of the Earth seem headlong, and not
admissible in nature by reason of its rapidity, worse than insane will be
the movement of the _Primum Mobile_ both for itself and the whole universe,
agreeing as it does with no other motion in any proportion or likeness. It
seems to Ptolemy and the Peripateticks that nature must be disordered, and
the framework and structure of this globe of ours be dissolved, by reason
of so swift a terrestrial revolution. The Earth's diameter is 1718 German
miles; the greatest elongation of the new Moon is 65, the least is 55
semi-diameters of the Earth: the greatest altitude of the half moon is 68,
the least 52: yet it is probable that its sphære is still larger and
deeper. The sun in its greatest eccentricity has a distance of 1142
semi-diameters of the Earth; Mars, Jupiter, Saturn, being slower in motion,
are so proportionately further remote from the Earth. The distances of the
firmament and of the fixed stars seem to the best mathematicians
inconceivable. Leaving out the ninth sphære, if the convexity of the
_Primum Mobile_ be duly estimated in proportion to the rest of the sphæres,
the vault of the _Primum Mobile_ must in one hour run through as much space
as is comprised in 3000 great circles of the Earth, for in the vault of the
firmament it would complete more than 1800; but what iron solidity can be
imagined so firm and tough as not to be disrupted and shattered to
fragments by a fury so great and a velocity so ineffable. The Chaldæans
indeed would have it that the heaven consists of light. In light, however,
there is no so-great firmness, neither is there in Plotinus' fiery
firmament, nor in the fluid or aqueous or supremely rare and transparent
heaven of the divine Moses, which does not cut off from our sight the
lights of the stars. We must accordingly reject the so deep-set error about
this so mad and furious a celestial velocity, and the forced retardation of
the rest of the heavens. Let theologians discard and wipe out with sponges
those old women's tales of so rapid a spinning round of the heavens
borrowed from certain inconsiderate philosophers. The sun is not propelled
by the sphære of Mars (if a sphære there be) and by his motion, nor Mars by
Jupiter, nor Jupiter by Saturn. The sphære, too, of the fixed stars, seems
well enough regulated except so far as motions which are in the Earth are
ascribed to the heavens, and bring about a certain change of phænomena. The
superiors do not exercise a despotism over the inferiors; for the heaven of
{219} philosophers, as of theologians, must be gentle, happy, and tranquil,
and not at all subject to changes: nor shall the force, fury, swiftness,
and hurry of a _Primum Mobile_ have dominion over it. That fury descends
through all the celestial sphæres, and celestial bodies, invades the
elements of our philosophers, sweeps fire along, rolls along the air, or at
least draws the chief part of it, conducts the universal æther, and turns
about fiery impressions (as if it were a solid and firm body, when in fact
it is a most refined essence, neither resisting nor drawing), leads captive
the superior. O marvellous constancy of the terrestrial globe, the only one
unconquered; and yet one that is holden fast, or stationary, in its place
by no bonds, no heaviness, by no contiguity with a grosser or firmer body,
by no weights. The substance of the terrestrial globe withstands and sets
itself against universal nature. Aristotle feigns for himself a system of
philosophy founded on motions simple and compound, that the heavens revolve
in a simple circle, its elements moving with a right motion, the parts of
the earth seeking the earth in straight lines, falling on its surface at
right angles, and tending together toward its centre, always, however, at
rest therein; accordingly also the whole Earth remains immovable in its
place, united and compacted together by its own weight. That cohæsion of
parts and aggregation of matter exist in the Sun, in the Moon, in the
planets, in the fixed stars, in fine in all those round bodies whose parts
cohære together and tend each to their own centres; otherwise the heaven
would fall, and that sublime ordering would be lost: yet these coelestial
bodies have a circular motion. Whence the Earth too may equally have her
own motion: and this motion is not (as some deem it) unsuitable for the
assembling or adverse to the generation of things. For since it is innate
in the terrestrial globe, and natural to it; and since there is nothing
external that can shock it, or hinder it by adverse motions, it goes round
without any ill or danger, it advances without being forced, there is
nothing that resists, nothing that by retiring gives way, but all is open.
For while it revolves in a space void of bodies, or in the incorporeal
æther, all the air, the exhalations of land and water, the clouds and
pendent meteors, are impelled along with the globe circularly: that which
is above the exhalations is void of bodies: the finest bodies and those
which are least cohærent almost void are not impeded, are not dissolved,
while passing through it. Wherefore also the whole terrestrial globe, with
all its adjuncts, moves bodily along, calmly, meeting no resistance.
Wherefore empty and superstitious is the fear that some weak minds have of
a shock of bodies (like Lucius Lactantius, who, in the fashion of the
unlettered rabble and of the most unreasonable men scoffs at an Antipodes
and at the sphærick ordering of the Earth all round). So for these reasons,
not only probable but manifest, does the diurnal rotation of the earth
seem, {220} since nature always acts through a few rather than through
many; and it is more agreeable to reason that the Earth's one small body
should make a diurnal rotation, than that the whole universe should be
whirled around. I pass over the reasons of the Earth's remaining motions,
for at present the only question is concerning its diurnal movement,
according to which it moves round with respect to the Sun, and creates a
natural day (which we call a nycthemeron[245]). And indeed Nature may be
thought to have granted a motion very suitable to the Earth's shape, which
(being sphærical) is revolved about the poles assigned it by Nature much
more easily and fittingly than that the whole universe, whose limit is
unknown and unknowable, should be whirled round; and than there could be
imagined an orbit of the _Primum Mobile_, a thing not accepted by the
ancients, which Aristotle even did not devise or accept as in any shape or
form existing beyond the sphære of the fixed stars; which finally the
sacred scriptures do not recognize any more than they do the revolution of
the firmament.
* * * * *