whether or not the Platonic Timæus affirmed the rotation of the
earth, they meant to designate the rotation of the earth in the
sense of Aristarchus, and in the sense in which modern astronomy
understands that capital fact. Now speaking the language of modern
astronomy, I think it certain that the rotation of the earth is
_not_ to be found affirmed in the Platonic Timæus; and I
agree with M. Boeckh when he says (Untersuch. p. 77), "Granting
that Aristotle ascribed to Plato the doctrine of the rotation of
the earth, he at least did not ascribe to him the doctrine as
Gruppe assumes, and as now understood." As between Gruppe--who
holds that the Platonic Timæus affirms the rotation of the earth,
and that Aristotle ascribes it to him, in our sense of the
words--and M. Boeckh, who denies this--I stand with the latter for
the negative. But when M. Boeckh assumes that the only alternative
doctrine is the immobility of the earth, and tries to show that
this doctrine is proclaimed in the Platonic Timæus--nay, that no
opposite doctrine _can_ be proclaimed, because the discourse
expressly announces the rotation of the sidereal heaven in
twenty-four hours--I am compelled to dissent from him as to the
conclusion, and to deny the cogency of his proof. M. Boeckh has
hardly asked himself the question, whether there was not some
other sense in which Plato might have affirmed it in the Timæus. I
have endeavoured to show that there was another sense; that there
are good analogies in Plato to justify the belief that he intended
to affirm the doctrine in that other sense; and that the comments
of Aristotle--while thoroughly pertinent, if we thus understand
the passage in the Timæus--become either irrelevant, dishonest, or
absurd, if we construe the passage as signifying either what is
maintained by M. Boeckh or what is maintained by Gruppe.
The eminent critics, whose opinions I here controvert, have been
apparently misled by the superior astronomical acquirements of the
present age, and have too hastily made the intellectual exigencies
of their own minds a standard for all other minds, in different
ages as well as in different states of cultivation. The question
before us is, not what doctrines are scientifically true or
scientifically compatible with each other, but what doctrines were
affirmed or implied by Plato. In interpreting him, we are required
to keep our minds independent of subsequent astronomical
theories. We must look, first and chiefly, to what is said by
Plato himself; next, if that be obscure, to the construction and
comments of his contemporaries so far as they are before us. In no
case is this more essential than in the doctrine of the rotation
of the earth, which in the modern mind has risen to its proper
rank in scientific importance, and has become connected with
collateral consequences and associations foreign to the ideas of
the ancient Pythagoreans, or Plato, or Aristotle. Unless we
disengage ourselves from these more recent associations, we cannot
properly understand the doctrine as it stands in the Platonic
Timæus.
This doctrine, as I have endeavoured to explain it, leads to an
instructive contrast between the cosmical theories of Plato (in
the Timæus) and Aristotle.
Plato conceives the kosmos as one animated and intelligent being
or god, composed of body and soul. Its body is moved and governed
by its soul, which is fixed or rooted in the centre, but stretches
to the circumference on all sides, as well as all round the
exterior. It has a perpetual movement of circular rotation in the
same unchanged place, which is the sort of movement most worthy of
a rational and intelligent being. The revolutions of the exterior
or sidereal sphere (Circle of the Same) depend on and are
determined by the revolutions of the solid cylinder or axis, which
traverses the kosmos in its whole diameter. Besides these, there
are various interior spheres or circles (Circles of the
Different), which rotate by distinct and variable impulses in a
direction opposite to the sidereal sphere. This latter is so much
more powerful than they, that it carries them all round with it;
yet they make good, to a certain extent, their own special
opposite movement, which causes their positions to be ever
changing, and the whole system to be complicated. But the grand
capital, uniform, overpowering, movement of the kosmos, consists
in the revolution of the solid axis, which determines that of the
exterior sidereal sphere. The impulse or stimulus to this movement
comes from the cosmical soul, which has its root in the centre.
Just at this point is situated the earth, "the oldest and most
venerable of intra-kosmic deities," packed round the centre of the
axis, and having for its function to guard and regulate those
revolutions of the axis, and through them those of the outer
sphere, on which the succession of day and night depends--as well
as to nurse mankind.
In all this we see that the ruling principle and force of the
kosmos ([Greek: to\ ê(gemoniko\n tou= ko/smou]) is made to
dwell in and emanate from _its centre_.
When we come to Aristotle, we find that the ruling principle or
force of the kosmos is placed, not in its centre, but in its
circumference. He recognises no solid revolving axis traversing
the whole diameter of the kosmos The interior of the kosmos is
occupied by the four elements--earth, water, air, fire--neither of
which can revolve except by violence or under the pressure of
extraneous force. To each of them rectilinear motion is
_natural_; earth moves naturally towards the centre--fire
moves naturally towards the circumference, away from the centre.
But the peripheral substance of the kosmos is radically distinct
from the four elements: rotatory motion in a circle is
_natural_ to it, and is the only variety of motion natural to
it. That it is moved at all, it owes to a _primum movens
immobile_ impelling it: but the two are coeternal, and the
motion has neither beginning nor end. That when moved, its motion
is rotatory and not rectilinear, it owes to its own nature. It
rotates perpetually, through its own nature and inherent virtue,
not by constraining pressure communicated from a centre or from a
soul. If constraint were required--if there were any contrary
tendency to be overcome--the revolving periphery would become
fatigued, and would require periods of repose; but, since in
revolving it only obeys its own peculiar nature, it persists for
ever without knowing fatigue. This peripheral or fifth essence,
perpetually revolving, is the divine, venerable, and commanding
portion of the kosmos, more grand and honourable than the interior
parts or the centre. Aristotle lays this down (De Coelo, ii. 13,
p. 293, b. 10) in express antithesis to the Pythagoreans, who
(like Plato) considered the centre as the point of grandeur and
command, placing fire in the centre for that reason. The earth has
no positive cosmical function in Aristotle; it occupies the centre
because all its parts have a natural movement towards the centre:
and it is unmoved because there _must be_ something in the
centre which is always stationary, as a contrary or antithesis to
the fifth essence or peripheral substance of the kosmos, which is
in perpetual rotation by its own immutable nature.
I do not here go farther into the exposition of these ancient
cosmical theories. I have adverted to Aristotle's doctrine only so
far as was necessary to elucidate, by contrast, that which I
believe to be the meaning of the Platonic Timæus about the
rotation of the earth.
LONDON: PRINTED BY W. CLOWES AND SONS, STAMFORD STREET,
AND CHARING CROSS.
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Transcriber's Note
The text is based on versions made available by the Internet Archive.
For the Greek transcriptions the following conventions have been used:
) is for smooth breathing; ( for hard; + for diaeresis; / for acute
accent; \ for grave; = for circumflex; | for iota subscript.
ch is used for chi, ph for phi, ps for psi, th for theta;
ê for eta and ô for omega; u is used for upsilon in all cases.
Corrections to the text, indicated with **
Text Correction
Ti/ma/iô Ti/maio
chore/ia chorei/a
ou)/ranon ou)rano\n
tetamenon tetame/non
e)ndeiknutai e)ndei/knutai]
forge force
Tima/iô| Timai/ô|
gegraptai ge/graptai]
e(ilei=sthai ei(lei=sthai
e)/pi\ e)pi\
a)utê=s au)tê=s