presence of a man who had solved in its essentials the problem of
the mechanism of the solar system. It appears from the words of
Archimedes that Aristarchus; had propounded his theory in
explicit writings. Unquestionably, then, he held to it as a
positive doctrine, not as a mere vague guess. We shall show, in a
moment, on what grounds he based his opinion. Had his teaching
found vogue, the story of science would be very different from
what it is. We should then have no tale to tell of a Copernicus
coming upon the scene fully seventeen hundred years later with
the revolutionary doctrine that our world is not the centre of
the universe. We should not have to tell of the persecution of a
Bruno or of a Galileo for teaching this doctrine in the
seventeenth century of an era which did not begin till two
hundred years after the death of Aristarchus. But, as we know,
the teaching of the astronomer of Samos did not win its way. The
old conservative geocentric doctrine, seemingly so much more in
accordance with the every-day observations of mankind, supported
by the majority of astronomers with the Peripatetic philosophers
at their head, held its place. It found fresh supporters
presently among the later Alexandrians, and so fully eclipsed the
heliocentric view that we should scarcely know that view had even
found an advocate were it not for here and there such a chance
record as the phrases we have just quoted from Archimedes. Yet,
as we now see, the heliocentric doctrine, which we know to be
true, had been thought out and advocated as the correct theory of
celestial mechanics by at least one worker of the third century
B.C. Such an idea, we may be sure, did not spring into the mind
of its originator except as the culmination of a long series of
observations and inferences. The precise character of the
evolution we perhaps cannot trace, but its broader outlines are
open to our observation, and we may not leave so important a
topic without at least briefly noting them.

Fully to understand the theory of Aristarchus, we must go back a
century or two and recall that as long ago as the time of that
other great native of Samos, Pythagoras, the conception had been
reached that the earth is in motion. We saw, in dealing with
Pythagoras, that we could not be sure as to precisely what he
himself taught, but there is no question that the idea of the
world's motion became from an early day a so-called Pythagorean
doctrine. While all the other philosophers, so far as we know,
still believed that the world was flat, the Pythagoreans out in
Italy taught that the world is a sphere and that the apparent
motions of the heavenly bodies are really due to the actual
motion of the earth itself. They did not, however, vault to the
conclusion that this true motion of the earth takes place in the
form of a circuit about the sun. Instead of that, they conceived
the central body of the universe to be a great fire, invisible
from the earth, because the inhabited side of the terrestrial
ball was turned away from it. The sun, it was held, is but a
great mirror, which reflects the light from the central fire. Sun
and earth alike revolve about this great fire, each in its own
orbit. Between the earth and the central fire there was,
curiously enough, supposed to be an invisible earthlike body
which was given the name of Anticthon, or counter-earth. This
body, itself revolving about the central fire, was supposed to
shut off the central light now and again from the sun or from the
moon, and thus to account for certain eclipses for which the
shadow of the earth did not seem responsible. It was, perhaps,
largely to account for such eclipses that the counter-earth was
invented. But it is supposed that there was another reason. The
Pythagoreans held that there is a peculiar sacredness in the
number ten. Just as the Babylonians of the early day and the
Hegelian philosophers of a more recent epoch saw a sacred
connection between the number seven and the number of planetary
bodies, so the Pythagoreans thought that the universe must be
arranged in accordance with the number ten. Their count of the
heavenly bodies, including the sphere of the fixed stars, seemed
to show nine, and the counter-earth supplied the missing body.

The precise genesis and development of this idea cannot now be
followed, but that it was prevalent about the fifth century B.C.
as a Pythagorean doctrine cannot be questioned. Anaxagoras also
is said to have taken account of the hypothetical counter-earth
in his explanation of eclipses; though, as we have seen, he
probably did not accept that part of the doctrine which held the
earth to be a sphere. The names of Philolaus and Heraclides have
been linked with certain of these Pythagorean doctrines. Eudoxus,
too, who, like the others, lived in Asia Minor in the fourth
century B.C., was held to have made special studies of the
heavenly spheres and perhaps to have taught that the earth moves.
So, too, Nicetas must be named among those whom rumor credited
with having taught that the world is in motion. In a word, the
evidence, so far as we can garner it from the remaining
fragments, tends to show that all along, from the time of the
early Pythagoreans, there had been an undercurrent of opinion in
the philosophical world which questioned the fixity of the earth;
and it would seem that the school of thinkers who tended to
accept the revolutionary view centred in Asia Minor, not far from
the early home of the founder of the Pythagorean doctrines. It
was not strange, then, that the man who was finally to carry
these new opinions to their logical conclusion should hail from
Samos.

But what was the support which observation could give to this
new, strange conception that the heavenly bodies do not in
reality move as they seem to move, but that their apparent motion
is due to the actual revolution of the earth? It is extremely
difficult for any one nowadays to put himself in a mental
position to answer this question. We are so accustomed to


<< previous page | next page >>

Jump to page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 |