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of this last kind is the shadow which produces the eclipse of the moon,
and this is so manifest that there can be no doubt remaining, that the
earth is exceeded in magnitude by the sun, a circumstance which is
indeed indicated by the silent declaration of nature herself. For why
does he recede from us at the winter half of the year[186]? That by
the darkness of the nights the earth may be refreshed, which otherwise
would be burned up, as indeed it is in certain parts; so great is his


The first among the Romans, who explained to the people at large the
cause of the two kinds of eclipses, was Sulpicius Gallus, who was
consul along with Marcellus; and when he was only a military tribune
he relieved the army from great anxiety the day before king Perseus
was conquered by Paulus[187]; for he was brought by the general into
a public assembly, in order to predict the eclipse, of which he
afterwards gave an account in a separate treatise. Among the Greeks,
Thales the Milesian first investigated the subject, in the fourth
year of the forty-eighth olympiad, predicting the eclipse of the sun
which took place in the reign of Alyattes, in the 170th year of the
City[188]. After them Hipparchus calculated the course of both these
stars for the term of 600 years[189], including the months, days, and
hours, the situation of the different places and the aspects adapted
to each of them; all this has been confirmed by experience, and could
only be acquired by partaking, as it were, in the councils of nature.
These were indeed great men, superior to ordinary mortals, who having
discovered the laws of these divine bodies, relieved the miserable
mind of man from the fear which he had of eclipses, as foretelling
some dreadful events or the destruction of the stars. This alarm is
freely acknowledged in the sublime strains of Stesichorus and Pindar,
as being produced by an eclipse of the sun[190]. And with respect to
the eclipse of the moon, mortals impute it to witchcraft, and therefore
endeavour to aid her by producing discordant sounds. In consequence of
this kind of terror it was that Nicias, the general of the Athenians,
being ignorant of the cause, was afraid to lead out the fleet, and
brought great distress on his troops[191]. Hail to your genius, ye
interpreters of heaven! ye who comprehend the nature of things, and who
have discovered a mode of reasoning by which ye have conquered both
gods and men[192]! For who is there, in observing these things and
seeing the labours[193] which the stars are compelled to undergo (since
we have chosen to apply this term to them), that would not cheerfully
submit to his fate, as one born to die? I shall now, in a brief and
summary manner, touch on those points in which we are agreed, giving
the reasons where it is necessary to do so; for this is not a work of
profound argument, nor is it less wonderful to be able to suggest a
probable cause for everything, than to give a complete account of a few
of them only.


It is ascertained that the eclipses complete their whole revolution
in the space of 223 months[194], that the eclipse of the sun takes
place only at the conclusion or the commencement of a lunation, which
is termed conjunction[195], while an eclipse of the moon takes place
only when she is at the full, and is always a little farther advanced
than the preceding eclipse[196]. Now there are eclipses of both these
stars in every year, which take place below the earth, at stated days
and hours; and when they are above it[197] they are not always visible,
sometimes on account of the clouds, but more frequently, from the
globe of the earth being opposed to the vault of the heavens[198]. It
was discovered two hundred years ago, by the sagacity of Hipparchus,
that the moon is sometimes eclipsed after an interval of five months,
and the sun after an interval of seven[199]; also, that he becomes
invisible, while above the horizon, twice in every thirty days, but
that this is seen in different places at different times. But the most
wonderful circumstance is, that while it is admitted that the moon is
darkened by the shadow of the earth, this occurs at one time on its
western, and at another time on its eastern side. And farther, that
although, after the rising of the sun, that darkening shadow ought
to be below the earth, yet it has once happened, that the moon has
been eclipsed in the west, while both the luminaries have been above
the horizon[200]. And as to their both being invisible in the space
of fifteen days, this very thing happened while the Vespasians were
emperors, the father being consul for the third time, and the son for
the second[201].


It is certain that the moon, having her horns always turned from the
sun, when she is waxing, looks towards the east; when she is waning,
towards the west. Also, that, from the second day after the change,
she adds 47-1/2 minutes[202] each day, until she is full, and again
decreases at the same rate, and that she always becomes invisible when
she is within 14 degrees of the sun. This is an argument of the greater
size of the planets than of the moon, since these emerge when they
are at the distance of 7 degrees only[203]. But their altitude causes
them to appear much smaller, as we observe that, during the day, the
brightness of the sun prevents those bodies from being seen which are
fixed in the firmament, although they shine then as well as in the
night: that this is the case is proved by eclipses, and by descending
into very deep wells.


The three planets, which, as we have said, are situated above the
sun[205], are visible when they come into conjunction with him.
They rise visibly[206] in the morning, when they are not more than
11 degrees from the sun[207]; they are afterwards directed by the
contact of his rays[208], and when they attain the trine aspect,
at the distance of 120 degrees, they take their morning stationary
positions[209], which are termed primary; afterwards, when they are
in opposition to the sun, they rise at the distance of 180 degrees
from him. And again advancing on the other side to the 120th degree,
they attain their evening stations, which are termed secondary, until
the sun having arrived within 12 degrees of them, what is called their
evening setting becomes no longer visible[210]. Mars, as being nearer
to the sun, feels the influence of his rays in the quadrature, at the
distance of 90 degrees, whence that motion receives its name, being
termed, from the two risings, respectively the first and the second
nonagenarian[211]. This planet passes from one station to another in
six months, or is two months in each sign; the two other planets do not
spend more than four months in passing from station to station.

The two inferior planets are, in like manner, concealed in their
evening conjunction, and, when they have left the sun, they rise in
the morning the same number of degrees distant from him. After having
arrived at their point of greatest elongation[212], they then follow
the sun, and having overtaken him at their morning setting, they
become invisible and pass beyond him. They then rise in the evening,
at the distances which were mentioned above. After this they return
back to the sun and are concealed in their evening setting. The star
Venus becomes stationary when at its two points of greatest elongation,
that of the morning and of the evening, according to their respective
risings. The stationary points of Mercury are so very brief, that they
cannot be correctly observed.


The above is an account of the aspects and the occultations of the
planets, a subject which is rendered very complicated by their motions,
and is involved in much that is wonderful; especially, when we observe
that they change their size and colour, and that the same stars at
one time approach the north, and then go to the south, and are now
seen near the earth, and then suddenly approach the heavens. If on
this subject I deliver opinions different from my predecessors, I
acknowledge that I am indebted for them to those individuals who first
pointed out to us the proper mode of inquiry; let no one then ever
despair of benefiting future ages.

But these things depend upon many different causes. The first cause is
the nature of the circles described by the stars, which the Greeks term
_apsides_[213], for we are obliged to use Greek terms. Now each of the
planets has its own circle, and this a different one from that of the
world[214]; because the earth is placed in the centre of the heavens,
with respect to the two extremities, which are called the poles, and
also in that of the zodiac, which is situated obliquely between them.
And all these things are made evident by the infallible results which
we obtain by the use of the compasses[215]. Hence the apsides of the
planets have each of them different centres, and consequently they have
different orbits and motions, since it necessarily follows, that the
interior apsides are the shortest.

(16.) The apsides which are the highest from the centre of the earth
are, for Saturn, when he is in Scorpio, for Jupiter in Virgo, for
Mars in Leo, for the Sun in Gemini, for Venus in Sagittarius, and for
Mercury in Capricorn, each of them in the middle of these signs; while
in the opposite signs, they are the lowest and nearest to the centre
of the earth[216]. Hence it is that they appear to move more slowly
when they are carried along the highest circuit; not that their actual
motions are accelerated or retarded, these being fixed and determinate
for each of them; but because it necessarily follows, that lines drawn
from the highest apsis must approach nearer to each other at the
centre, like the spokes of a wheel; and that the same motion seems to
be at one time greater, and at another time less, according to the
distance from the centre.

Another cause of the altitudes of the planets is, that their highest
apsides, with relation to their own centres, are in different signs
from those mentioned above[217]. Saturn is in the 20th degree of Libra,
Jupiter in the 15th of Cancer, Mars in the 28th of Capricorn, the Sun
in the 19th of Aries, Venus in the 27th of Pisces, Mercury in the 15th
of Virgo, and the Moon in the 3rd of Taurus.

The third cause of the altitude depends on the form of the heavens,
not on that of the orbits; the stars appearing to the eye to mount
up and to descend through the depth of the air[218]. With this cause
is connected that which depends on the latitude of the planets and
the obliquity of the zodiac. It is through this belt that the stars
which I have spoken of are carried, nor is there any part of the world
habitable, except what lies under it[219]; the remainder, which is at
the poles, being in a wild desert state. The planet Venus alone exceeds
it by 2 degrees, which we may suppose to be the cause why some animals
are produced even in these desert regions of the earth. The moon also
wanders the whole breadth of the zodiac, but never exceeds it. Next
to these the planet Mercury moves through the greatest space; yet out
of the 12 degrees (for there are so many degrees of latitude in the
zodiac[220]), it does not pass through more than 8, nor does it go
equally through these, 2 of them being in the middle of the zodiac, 4
in the upper part, and 2 in the lower part[221]. Next to these the Sun
is carried through the middle of the zodiac, winding unequally through
the two parts of his tortuous circuit[222]. The star Mars occupies the
four middle degrees; Jupiter the middle degree and the two above it;
Saturn, like the sun, occupies two[223]. The above is an account of
the latitudes as they descend to the south or ascend to the north[224].
Hence it is plain that the generality of persons are mistaken in
supposing the third cause of the apparent altitude to depend on the
stars rising from the earth and climbing up the heavens. But to refute
this opinion it is necessary to consider the subject with very great
minuteness, and to embrace all the causes.

It is generally admitted, that the stars[225], at the time of their
evening setting, are nearest to the earth, both with respect to
latitude and altitude[226], that they are at the commencement of both
at their morning risings, and that they become stationary at the middle
points of their latitudes, what are called the ecliptics[227]. It is,
moreover, acknowledged, that their motion is increased when they are
in the vicinity of the earth, and diminished when they are removed to
a greater altitude[228]; a point which is most clearly proved by the
different altitudes of the moon. There is no doubt that it is also
increased at the morning risings[229], and that the three superior
planets are retarded, as they advance from the first station to the
second. And since this is the case, it is evident, that the latitudes
are increased from the time of their morning risings, since the motions
afterwards appear to receive less addition; but they gain their
altitude in the first station, since the rate of their motion then
begins to diminish[230], and the stars to recede.

And the reason of this must be particularly set forth. When the planets
are struck by the rays of the sun, in the situation which I have
described, _i. e._ in their quadrature, they are prevented from holding
on their straight forward course, and are raised on high by the force
of the fire[231]. This cannot be immediately perceived by the eye, and
therefore they seem to be stationary, and hence the term station is
derived. Afterwards the violence of the rays increases, and the vapour
being beaten back forces them to recede.

This exists in a greater degree in their evening risings, the sun being
then turned entirely from them, when they are drawn into the highest
apsides; and they are then the least visible, since they are at their
greatest altitude and are carried along with the least motion, as much
less indeed as this takes place in the highest signs of the apsides. At
the time of the evening rising the latitude decreases and becomes less
as the motion is diminished, and it does not increase again until they
arrive at the second station, when the altitude is also diminished;
the sun’s rays then coming from the other side, the same force now
therefore propels them towards the earth which before raised them into
the heavens, from their former triangular aspect[232]. So different is
the effect whether the rays strike the planets from below or come to
them from above. And all these circumstances produce much more effect
when they occur in the evening setting. This is the doctrine of the
superior planets; that of the others is more difficult, and has never
been laid down by any one before me[233].


I must first state the cause, why the star Venus never recedes from the
sun more than 46 degrees, nor Mercury more than 23[234], while they
frequently return to the sun within this distance[235]. As they are
situated below the sun, they have both of them their apsides turned in
the contrary direction; their orbits are as much below the earth as
those of the stars above mentioned are above it, and therefore they
cannot recede any farther, since the curve of their apsides has no
greater longitude[236]. The extreme parts of their apsides therefore
assign the limits to each of them in the same manner, and compensate,
as it were, for the small extent of their longitudes, by the great
divergence of their latitudes[237]. It may be asked, why do they not
always proceed as far as the 46th and the 23rd degrees respectively?
They in reality do so, but the theory fails us here. For it would
appear that the apsides are themselves moved, as they never pass over
the sun[238]. When therefore they have arrived at the extremities
of their orbits on either side, the stars are then supposed to have
proceeded to their greatest distance; when they have been a certain
number of degrees within their orbits, they are then supposed to return
more rapidly, since the extreme point in each is the same. And on this
account it is that the direction of their motion appears to be changed.
For the superior planets are carried along the most quickly in their
evening setting, while these move the most slowly; the former are at
their greatest distance from the earth when they move the most slowly,
the latter when they move the most quickly. The former are accelerated
when nearest to the earth, the latter when at the extremity of the
circle; in the former the rapidity of the motion begins to diminish at
their morning risings, in the latter it begins to increase; the former
are retrograde from their morning to their evening station, while Venus
is retrograde from the evening to the morning station. She begins to
increase her latitude from her morning rising, her altitude follows the
sun from her morning station, her motion being the quickest and her
altitude the greatest in her morning setting. Her latitude decreases
and her altitude diminishes from her evening rising, she becomes
retrograde, and at the same time decreases in her altitude from her
evening station.

Again, the star Mercury, in the same way, mounts up in both
directions[239] from his morning rising, and having followed the
sun through a space of 15 degrees, he becomes almost stationary for
four days. Presently he diminishes his altitude, and recedes from
his evening setting to his morning rising. Mercury and the Moon are
the only planets which descend for the same number of days that they
ascend. Venus ascends for fifteen days and somewhat more; Saturn and
Jupiter descend in twice that number of days, and Mars in four times.
So great is the variety of nature! The reason of it is, however,
evident; for those planets which are forced up by the vapour of the sun
likewise descend with difficulty.


There are many other secrets of nature in these points, as well as the
laws to which they are subject, which might be mentioned. For example,
the planet Mars, whose course is the most difficult to observe[241],
never becomes stationary when Jupiter is in the trine aspect, very
rarely when he is 60 degrees from the sun, which number is one-sixth of
the circuit of the heavens[242]; nor does he ever rise in the same sign
with Jupiter, except in Cancer and Leo. The star Mercury seldom has
his evening risings in Pisces, but very frequently in Virgo, and his
morning risings in Libra; he has also his morning rising in Aquarius,
very rarely in Leo. He never becomes retrograde either in Taurus or
in Gemini, nor until the 25th degree of Cancer. The Moon makes her
double conjunction with the sun in no other sign except Gemini, while
Sagittarius is the only sign in which she has sometimes no conjunction
at all. The old and the new moon are visible on the same day or night
in no other sign except Aries, and indeed it has happened very seldom
to any one to have witnessed it. Prom this circumstance it was that the
tale of Lynceus’s quick-sightedness originated[243]. Saturn and Mars
are invisible at most for 170 days; Jupiter for 36, or, at the least,
for 10 days less than this; Venus for 69, or, at the least, for 52;
Mercury for 13, or, at the most, for 18[244].


The difference of their colour depends on the difference in their
altitudes; for they acquire a resemblance to those planets into the
vapour of which they are carried, the orbit of each tinging those
that approach it in each direction. A colder planet renders one that
approaches it paler, one more hot renders it redder, a windy planet
gives it a lowering aspect, while the sun, at the union of their
apsides, or the extremity of their orbits, completely obscures them.
Each of the planets has its peculiar colour[245]; Saturn is white,
Jupiter brilliant, Mars fiery, Lucifer is glowing, Vesper refulgent,
Mercury sparkling, the Moon mild; the Sun, when he rises, is blazing,
afterwards he becomes radiating. The appearance of the stars, which
are fixed in the firmament, is also affected by these causes. At one
time we see a dense cluster of stars around the moon, when she is only
half-enlightened, and when they are viewed in a serene evening; while,
at another time, when the moon is full, there are so few to be seen,
that we wonder whither they are fled; and this is also the case when
the rays of the sun, or of any of the above-mentioned bodies[246], have
dazzled our sight. And, indeed, the moon herself is, without doubt,
differently affected at different times by the rays of the sun; when
she is entering them, the convexity of the heavens[247] rendering them
more feeble than when they fall upon her more directly[248]. Hence,
when she is at a right angle to the sun, she is half-enlightened; when
in the trine aspect, she presents an imperfect orb[249], while, in
opposition, she is full. Again, when she is waning, she goes through
the same gradations, and in the same order, as the three stars that are
superior to the sun[250].


The Sun himself is in four different states; twice the night is equal
to the day, in the Spring and in the Autumn, when he is opposed to the
centre of the earth[251], in the 8th degree of Aries and Libra[252].
The length of the day and the night is then twice changed, when the
day increases in length, from the winter solstice in the 8th degree of
Capricorn, and afterwards, when the night increases in length from the
summer solstice in the 8th degree of Cancer[253]. The cause of this
inequality is the obliquity of the zodiac, since there is, at every
moment of time, an equal portion of the firmament above and below the
horizon. But the signs which mount directly upwards, when they rise,
retain the light for a longer space, while those that are more oblique
pass along more quickly.


It is not generally known, what has been discovered by men who are the
most eminent for their learning, in consequence of their assiduous
observations of the heavens, that the fires which fall upon the earth,
and receive the name of thunder-bolts, proceed from the three superior
stars[254], but principally from the one which is situated in the
middle. It may perhaps depend on the superabundance of moisture from
the superior orbit communicating with the heat from the inferior, which
are expelled in this manner[255]; and hence it is commonly said, the
thunder-bolts are darted by Jupiter. And as, in burning wood, the burnt
part is cast off with a crackling noise, so does the star throw off
this celestial fire, bearing the omens of future events, even the part
which is thrown off not losing its divine operation. And this takes
place more particularly when the air is in an unsettled state, either
because the moisture which is then collected excites the greatest
quantity of fire, or because the air is disturbed, as if by the
parturition of the pregnant star.


Many persons have attempted to discover the distance of the stars
from the earth, and they have published as the result, that the
sun is nineteen times as far from the moon, as the moon herself is
from the earth[256]. Pythagoras, who was a man of a very sagacious
mind, computed the distance from the earth to the moon to be 126,000
furlongs, that from her to the sun is double this distance, and that
it is three times this distance to the twelve signs[257]; and this was
also the opinion of our countryman, Gallus Sulpicius[258].


Pythagoras, employing the terms that are used in music, sometimes names
the distance between the Earth and the Moon a tone; from her to Mercury
he supposes to be half this space, and about the same from him to
Venus. From her to the Sun is a tone and a half; from the Sun to Mars
is a tone, the same as from the Earth to the Moon; from him there is
half a tone to Jupiter, from Jupiter to Saturn also half a tone, and

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