TO PROFESSOR LEWIS
CAMPBELL.
11 Scroope Terrace,
Cambridge, 26th February 1874.
Jackson has sent me a MS. of
yours about the
mechanism of the heavens(14). After the interpretation of 
, about which Greek appears to meet Greek as to whether it expresses
motion
or only configuration, the main point seems to be, What is
the motion and function of?
(alpha) Is it in one piece
with the sphere
of the stars? or (beta) with that of the sun? or (gama) is it fixed in
the earth ?
It is evidently a good stout
axle, not a mere
geometrical line, and it has some stiff work to do.
What is this work?
If the earth is fixed, and
the great shaft
has its bearings in a hole in the earth, then she (the earth) may, in
virtue
of her dignity and office, cause the axle to revolve,
carrying
with it the stars according to alpha, or the sun according
to beta. Thus the earth may be the cause of the motion of the Same
without
moving herself, as a spinster is the cause of the whirling
of the spindle, though she does not herself pirouette.
Or we may suppose the earth
to act as one who
twirls an expanded umbrella over his head about its stick
as
an axis, the holes in the same representing the stars. The objection to
this view (which seems to me to be Jowett's) is that in
stating
the relation between the earth and the axis, the earth is said to be
related
to the axis (packed or whirling as the case may be),
and not the axis to the earth. Now, I suppose that without
all
contradiction the less is related to the better. Here the earth is like
a ball of clay packed round a graft on the branch of
a tree, rather than like a field in which, by means of a rotatory
boring
tool, men bore for water.
But the business of the earth
is not so much
to keep the stars in motion as to effect the changes of night and
day.
This she may do either by rotating herself from W. to E., or by
controlling
the motion of the sun, by the help of the great shaft.
Now, if you always observe at
the same time
of night (a common practice), you find the eastern stars higher
every
day, and the western lower. All have the same motion, which carries
them
round from E. to W. in a year.
Mars, Jupiter, and Saturn, in
spite of their
wanderings go on the whole in the same direction, but slower.
Venus
and Mercury oscillate about the sun, and the moon goes the opposite
way—from
W. to E.
That this way of viewing the
matter was really
prevalent at one time is plain, from the expression the rising of
such
a star to denote not a time of night but a time of year. It means
either
(1) the day when the star rises, just before it is lost in
the brightness of the sun who follows it, or (2) the day when the star
is rising, when it just becomes visible after sunset.
Virgil, who speaks of stars rising, evidently had no
practical knowledge
of what he meant. Plato, if he sometimes gets hazy, is far clearer than
Virgil. Grote would place him far below Mr. Jellinger Symons, who
denied
the rotation of the moon, because Grote makes Plato say
that
both the heavens and the earth rotate both in the same
direction,
and with the same angular velocity.
I think I understand you to
make Plato make
the earth sit still and preside over the heavenly motions, and
so
become the artifices of day and night, like a policeman who swings his
bull's-eye round to his back. But his words are capable of
being used by the movers of the earth, as Milton says,
If earth, industrious
of herself, fetch day Travelling east.
I hope you will let me know
whether I have
not misunderstood both you, Plato, and the Truth. I have
never
thanked you for your Œdipus, etc., which I have enjoyed. But at present
I am all day at the Laboratory, which is emerging
from
chaos, but is not yet cleared of gas-men, who are the laziest and most
permanent of all the gods who have been hatched under
heaven(15).
Mrs. Maxwell joins me in kind regards to Mrs. Campbell
and yourself.—Your
afft. friend.
