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vals, as did also the Moon, the planets, and the stars ; but, 
then, how could they be fixed in one revolving dome, when the 
orbits of the two former were elevated or depressed at various 
seasons and periods of the year ? the Sun requiring a year, and 
the Moon about twenty-nine days to complete its cycle ; five 
of the stars wandering Avithout any apparent order, but all 
the rest fixed and immovable, as if to silence the doubts of the 
heterodox, and to confound the calculations of ingenious specu- 
lators. But to give a final bloiv to the theory of the Earth’s 
central position and the one revolving firmament, it was dis- 
covered, after a lapse of many centuries of careful observation, 
that the Sun’s path in the sky was gradually changing, to speak 
familiarly ; that it did not rise and set with the same stars at 
the same period every year, but Avas gradually moving towards 
the Avest, leaving the fixed stars behind it.* 
Many and ingenious were the theories by Avhicli the appa- 
rently eccentric motions of the heavenly bodies were sought to 
be explained. The circumstances to Avliich we have referred, 
and the discovery of the true nature of eclipses, rendered the 
theory of one single solid firmament equi-distant in every part 
from the central Earth around which it revolved, quite unten- 
able ; and the first important step in ancient cosmogony Avas 
that which divided the crystalline vault of heaven into belts or 
zones more or less distant from the Earth ; each belt containing 
its own section of the heavenly host. 
The Moon was known to be nearer to the Earth than the Sun, 
for her dark body was found to interpose between these two 
spheres, and she therefore was placed in the nearest zone : 
next came the zones of the Sun, planets, and fixed stars respec- 
tively, each making its own appropriate revolution. 
This theory met one difficulty, namely, the variable distances 
of the different heavenly bodies from the Earth, and even to 
some extent, the regular elevation and depression of them orbits ; 
but it was not sufficient to account for the slow changes which 
took place in the latter, and to explain this phenomenon, Pytha- 
gorasf supposed a motion in the Earth itself, and removed 
it from its central position in the Universe. His cosmical 
system was, however, very vague, and was made up of a 
strange compound of fiction and fact. Such as it was, hoAV- 
ever, it maintained its position until the true nature of the Solar 
system was revealed 2,000 years subsequently by Copernicus, 
the great Polish astronomer. 
We shall now present to our readers the Pythagorean system, 
as enunciated by his followers, in contrast with the earliest 
* The precession of the Equinoxes. See any Handbook of Astronomy. 
t About 500 years b.c. 
