The
Sand Reckoner
Chapter I
There are some, king Gelon, who think that the number of the sand is
infinite in multitude; and I mean by the sand not only that
which exists about Syracuse and the rest of Sicily but also that which
is found in every region whether inhabited or uninhabited.
Again there are some who, without regarding it as infinite, yet think
that no number has been named which is great enough to
exceed its multitude. And it is clear that they who hold this view,
if they imagined a mass made up of sand in other respects as
large as the mass of the earth filled up to a height equal to that
of the highest of the mountains, would be many times further still
from recognizing that any number could be expressed which exceeded
the multitude of the sand so taken. But I will try to show
you by means of geometrical proofs, which you will be able to follow,
that, of the numbers named by me and given in the work
which I sent to Zeuxippus, some exceed not only the number of the mass
of sand equal in magnitude to the earth filled up in the
way described, but also that of a mass equal in magnitude to the universe.
Now you are aware that `universe' is the name given by most astronomers
to the sphere whose centre is the centre of the earth and whose radius
is equal to the straight line between the centre of the sun and the centre
of the earth. This is the common account, as you have heard from astronomers.
But Aristarchus of Samos brought out a book consisting of some hypotheses,
in which the premisses lead to the result that the universe is many times
greater than that now so called. His hypotheses are that the fixed stars
and the sun remain unmoved, that the earth revolves about the sun in the
circumference of a circle, the sun lying in the middle of the orbit, and
that the sphere of the fixed stars, situated about the same centre as the
sun, is so great that the circle in which he supposes the earth to revolve
bears such a proportion to the distance of the fixed stars as the centre
of the sphere bears to its surface. Now it is easy to see that this is
impossible. For, since the centre of the sphere has no magnitude, we cannot
conceive it to bear any ratio whatever to the surface of the sphere. We
must however take Aristarchus to mean this: Since we conceive the earth
to be, as it were, the centre of the universe, the ratio which the earth
bears to what we describe as the ``universe'' is the same as the ratio
which the sphere containing the circle in which he supposes the earth to
revolve bears to the sphere of the fixed stars. For he adapts the proofs
of his results to a hypothesis of this kind, and in particular he appears
to suppose the magnitude of the sphere in which he represents the earth
as moving to be equal to what we call the "universe.''
I say then that, even if a sphere were made up of sand as great as Aristarchus supposes the sphere of the fixed stars to be, I shall still prove that, of the numbers named in the {\sl Principles,} some exceed in multitude the number of the sand which is equal in magnitude to the sphere referred to, provided that the following assumptions be made:
1. The perimeter of the earth is three hundred myriad stadia
and no greater, though some have tried to show, as you know, that
this length is thirty myriad stadia. But I, surpassing this number
and setting the size of the earth as being ten times that evaluated
by my predecessors, suppose that its perimeter is three hundred myriad
stadia and not greater.
2. Secondly, that the diameter of the earth is greater than the diameter of the moon and that the diameter of the sun is greater than the diameter of the earth. My hypothesis is in agreement with most earlier astronomers.
3. Third hypothesis: the diameter of the sun is thirty times larger than that of the moon and not greater, even though among earlier astronomers Eudoxus tried to show it as nine times larger and Pheidias, my father, as twelve times larger, while Aristarchus tried to show that the diameter of the sun lies between a length of eighteen moon diameters and a length of twenty four moon diameters; but I, surpassing this number as well, suppose, so that my proposition may be established without dispute, that the diameter of the sun is equal to thirty moon diameters, and not more.
4. Finally, we state that the diameter of the sun is greater
than the side of the polygon of one thousand sides inscribed in the great
circle of the universe. I make this hypothesis because Aristarchus found
that the sun appears as the seven hundred and twentieth part of the circle
of the zodiac. While examining this question I have, for my part tried
in the following manner, to show with the aid of instruments, the angle
subtended by the sun, having its vertex at the eye. Clearly, the exact
evaluation of this angle is not easy since neither vision, hands, nor the
instruments required to measure this angle are reliable enough to measure
it precisely. But this does not seem to me to be the place to discuss this
question at length, especially because observations of this type have often
been reported. For the purposes of my proposition, it suffices to find
an angle that is not greater than the angle subtended at the sun with vertex
at the eye and to then find another angle which is not less than the angle
subtended by the sun with vertex at the eye. A long ruler having been placed
on a vertical stand placed in the direction of where the rising sun could
be seen, and a little cylinder was put vertically on the ruler immediately
after sunrise. Then, the sun being at the horizon, and could be looked
at directly, the ruler was oriented towards the sun and the eye at the
extremity of the ruler. The cylinder being placed between the sun and the
eye, occludes the sun. The cylinder is then moved further away from the
eye and as soon as a small piece of the sun begins to show itself from
each side of the cylinder, it is fixed. If the eye were really to see from
one point, tangents to the cylinder produced from the end of the ruler
where the eye was placed would make an angle less than the angle subtended
by the sun with vertex at the eye. But since the eyes do not see from a
unique point, but from a certain size, one takes a certain size, of round
shape, not smaller than the eye and one places it at the extremity of the
ruler where the eye had been placed. If one produces tangents to this size
and to the cylinder, the angle between these lines is smaller than the
angle subtended by the sun with vertex at the eye. And here is the way
one finds the size not smaller to the eye: one takes two small thin cylinders
of the same width, one white, the other not, and one places them in front
of the eye, the white one at some distance, and the other one which is
not white as close to the eye as possible without touching the face. In
this way, if the small cylinders chosen are smaller than the eye, the cylinder
neighbouring the eye is encompassed in the visual field and the eye sees
the white cylinder. If the cyclinders are much smaller, the white one is
completely seen. If they are not much smaller, one sees parts of the white
one and parts of the one neighboring the eye. But if one choose cylinders
of appropiate width one of them occludes the other without covering a larger
space. It is therefore clear that the width of cylinders producing this
effect is not smaller than the dimensions of the eye. As for the angle
not smaller than the angle subtending the sun with vertex at the eye, it
was taken as follows: The cylinder being placed on the ruler at a distance
which blocks all of the sun, if one produces from the end of the ruler
where the eye is placed tangent lines to the cylinder, the angle made by
these lines is not smaller than the angle subtended by the sun with vertex
at the eye. A right angle being measured by the angles taken in this way,
the angle placed at the point is found to be the one hundred and sixty
fourth part of a right angle, while the smallest angle is found to be greater
to the two hundredth part of a right angle. It is therefore clear that
the angle subtended by the sun with vertex at the eye is also smaller than
the one hundred and sixty fourth part of a right angle, and greater than
the two hundredth part of a right angle. With these measurements completed,
one shows that the diameter of the sun is greater than the side of the
polygon with one thousand sides inscribed in the great circle of the universe.
Let us imagine then a plane passing through the centre of the sun, the
centre of the earth and the eye at the instant when the sun finds itself
a little above the horizon; that this plane cuts the universe at the circle
$AB\Gamma$, the earth at the circle $\Delta E Z$, and the sun at the circle
$\Sigma H$. Let $\Theta$ be the centre of the earth, $K$ the centre of
the sun, and let $\Delta$ be the eye; we produce from $\Delta$ the tangents
$\Delta \Lambda$, $\Delta \Xi$ to the circle $\Sigma H$ with contact points
$N$ and $T$, and from $\Theta$ the tangents $\Theta M$ and $\Theta O$ with
contact points $X$ and $P$. Let $A$ and $B$ be the points of intersection
of the circle AB\Gamma$ and the lines $\Theta M$ and $\Theta O$. Thus $\Theta
K$ is greater than $\Delta K$ from the hypothesis that the sun finds itself
above the horizon. If follows that the angle contained between $\Delta
\Lambda$ and $\Delta \Xi$ is greater than the angle contained between $\Theta
M$ and $\Theta O$. But the angle contained between $\Delta \Lambda$ and
$\Delta \Xi$ is greater than the two hundredth part of a right angle since
it is equal to the angle subtended by the sun with vertex at the eye; and
consequently, the angle contained between $\Theta M$ and $\Theta O$ is
less than the one hundred and sixty fourth part of a right angle and the
segment of the line $AB$ is less than the chord of the circular sector
which is the six hundred and sixty fifth part of the circle $AB\Gamma$.
But the perimeter of the polygon in question has with the radius of the
circle $AB\Gamma$ a ratio less than fourty four to seven because the ratio
of the perimeter of every polygon inscribed in a circle to the radius of
the circle is less than the ratio fourty four to seven. You know, in fact,
that I have shown that in every circle the perimeter is greater, by a quantity
smaller than the seventh, than triple the diameter and that the perimeter
of the inscribed polygon is smaller than this circumference. The ratio
of $BA$ to $\Theta K$ is thus less than the ratio of eleven to one thousand
one hundred and fourty eight. It follows that $BA$ is smaller than
a hundredth $\Theta K$. But the diameter of the circle $\Sigma H$ is equal
to $BA$ since half of $\Sigma H$, the segment $\Phi A$, is equal to $KP$.
The segments $\Theta K$ and $\Theta A$ are in fact equal and their endpoints
perpendiculars are produced under the same angle ??. It is thus clear that
the diameter of the circle $\Sigma H$ is less than the hundredth part of
$\Theta K$. Moreover, the diameter $E\Theta \Upsilon $ is less than the
diameter of the circle $\Sigma H$ since the circle $\Delta E Z$ is less
than the circle $\Sigma H$. If follows that the sum of $\Theta \Upsilon$
and $K\Sigma$ is less than the hundredth part of $\Theta K$ so that the
ratio of $\Theta K$ to $\Upsilon K$ is less than the ratio of one hundred
to ninety nine. And as long as $\Sigma \Upsilon$ is less than $\Delta T$,
the ratio of $\Theta P$ to $\Delta T$ is less than the ratio of one hundred
to ninety nine. But since in the right triangles ?? $\Theta KP$ and $\Delta
KT$ the sides $KP$ and $KT$ are equal and the sides $\Theta P$ and $\Delta
T$ unequal, $\Theta P$ being larger, the ratio of the angle contained between
the sides $\Delta T$ and $\Delta K$ to the angle contained between the
$\Theta P$ and $\Theta K$ is greater than the ratio of $\Theta K$ to $\Delta
K$, but less than the ratio of $\Theta P$ to $\Delta T$. For if in two
right triangles two of the sides containing the right angle are equal and
the two others unequal, then the larger angle opposite the unequal sides
has to the smaller of these angles a ratio greater than the ratio of the
greater hypotenuse to the smaller, but smaller than the ratio of the greater
side to the right angle to the smaller. As a consequence, the ratio of
the angle contained between $\Delta \Lambda$ and $\Delta \Xi$ to the angle
contained between $\Theta O$ and $\Theta M$ is less than the ratio of $\Theta
P$ to $\Delta T$ which is itself less than the ratio of one hundred to
ninety nine. It follows that the ratio of the angle contained between $\Delta
\Lambda$ and $\Delta \Xi$ is greater than the two hundredth part of a right
angle, the angle contained between $\Theta M$ and $\Theta O$ is greater
than ninety nine twenty thousandths of a right angle; and as a consequence,
this angle is greater than one two hundred and third of a right angle.
The segment $BA$ is thus greater than the chord of the sector which is
a eight hundred and twelvth part of the circle $AB\Gamma$. But it is to
the line segment $AB$ that the diameter of the circle is equal to. It is
therefore clear that the diameter of the circle is greater than the side
of the polygon of one thousand sides.
Chapter II
These relations being given, one can also show that the diameter of
the universe is less than a line equal to a myriad diameters
of the earth and that, moreover, the diameter of the universe is less
than a line equal to one hundred myriad myriad stadia. As soon as one has
accepted the fact that the diameter of the sun is not greater than thirty
moon diameters and that the diameter of the earth is greater than the diameter
of the moon, it is clear that the diameter of the sun is less than thirty
diamters of the earth. As we have also shown that the diameter of the sun
is greater than the side of the polygon of one thousand sides inscribed
in the great circle of the universe, it is clear that the perimeter of
the indicated polygon of one thousand sides is less than one thousand
diameters of the sun. But the diameter of the sun is less than thirty
earth diameters so it follows that the perimeter of the polygon
of one thousand sides is less than thirty thousand earth diameters.
Given that the perimeter of the polygon of one thousand sides is less than
thirty thousand earth diameters and greater than three diameters of the
universe--we have shown in fact that in every
circle the diameter is less than one third the perimeter of any regular
polygon inscribed in the circle for which the number of sides is greater
than that of the hexagon--the diameter of the universe is less than a myriad
earth diameters. One has thus shown that the diameter of the universe is
less than a myriad earth diameters; that the diameter of the universe is
less than one hundred
myriad myriad stadia, which comes out of the following argument; since,
in fact, we have supposed that the perimeter of the earth is not greater
than three hundred myriad stadia and that the perimeter?? of the earth
is greater than triple the diameter because in every circle the circumference
is greater than triple the diameter, it is clear that the diameter of the
earth is less than one hundred myriad stadia. Given that the diameter of
the universe is less than a myriad earth diameters it is clear that the
diameter of the world is less than one hundred myriad myriad stadia. These
are my hypotheses regarding sizes and distances. Here now is what I assume
about the subject of sand: if one has a quantity of sand whose volume does
not exceed that of a poppy--seed, the number of these grains of sand will
not exceed a myriad and the diamter of the grains will not be less than
a fourtieth of a finger--breadth. I make these hypotheses following these
observations: poppy seeds having been placed on a polished ruler in a straight
line in such a way that each touches the next, twenty five seeds occupied
a space greater than one finger--breadth. I will suppose that the diameter
of the grains is smaller and to be about a fourtieth of a finger--breadth
for the purpose of removing any possiblity of criticizing the proof of
my proposition
Chapter III
These are thus my hypotheses; but I think it useful to explain myself
about the naming of numbers so that those readers, not
having been able to get hold of my book addressed to Zeuxippus, may
not be thrown off by the absence in this book of any
indication ?? of the subject of this nomenclature. It so happens that
tradition has given to us the name of numbers up to a myriad
and we distinguish enough numbers surpassing a myriad by enumerating
the number of myriads until a myriad myriad. We will
therefore call first numbers those which, after the current nomenclature,
go up to a myriad myriad. We will call units of second
numbers the myriad myriad of first numbers and we will count among
second number units and, starting with units, tens, hundreds, thousands,
myriads, until a myriad myriad. We will call once again call third numbers
a myriad myriad of second numbers and we will count among third numbers,
starting with units, tens, hundreds, thousands, myriads, until the myriad
myriad. In the same way we will call units of fourth numbers a myriad myriad
of third numbers, units of fifth numbers a myriad myriad of fourth numbers,
and continuing in this way the numbers will be distinguishable until the
myriad myriad of of myriad myriad numbers. Numbers named in this
way could certainly suffice but it is possible to go still further. Let
us in fact call numbers of the first period the numbers given up to this
point and units of first numbers of the second period the last number of
the first period. Furthermore, call the unit of second numbers of the second
period the myriad myriad of first numbers of the second period. In the
same way, the last of these numbers will be called the unit of third numbers
of the second period, and continuing in this way, progressing through the
numbers of the second period will have their names up to the myriad myriad
numbers myriad myriad??. The last number of the second period will be in
turn called the unit of the first numbers of the third period, and so forth
until the myriad myriad numbers myriad myriad of the myriad myriad period.
These numbers having been named, given?? numbers ordered by size starting
from unity and if the number closest to unity is the
tens, the first eight of these including the unity will belong to the
numbers called first numbers, the following eight numbers called
second, and the others in the same way by the distance of their octad
of numbers to the first octad of numbers. The eigth number of the first
octad is thus one thousand myriads and the first number of the second octad,
since it multiplies by ten the number preceding it, will be a myriad myriad
and this number is the unit of the second numbers. The eight number of
the second octad is one thousand myriad of second numbers. The first number
of the third octad will once again be, as it multiplies by ten the preceding
number, a myriad myriad of second numbers, the unity of the third numbers.
It is clear that the same will hold as
indicated for any octad.
It is useful to know what follows. If numbers are in proportion starting
from unity and some which are in the same proportion are multiplied to
each other, then the product will be increased from the larger of the factors
by as many numbers as the smaller
number is ?? in proportion to unity and it will be increased from unity
by the sum minus one of the numbers away from unity??. In fact, let $A,
B, \Gamma, E, Z, H, \Theta, I, K,\Lambda$ in proportion starting from unity,
and let $A$ be unity. Multiply $\Delta$ by $\Theta$ and let $X$ be the
product. Let us take in the proportion $\Lambda$ whose distance to $\Theta$
holds as many numbers as the distance from $\Delta$ to unity. It must be
shown that $X$ equals $\Lambda$. If, among the numbers in proportion, the
distance from $\Delta$ to $A$ counts as many numbers as that from $\Lambda$
to $\Theta$, the ratio of $\Delta$ to $A$ equals the ratio of $\Lambda$
to $\Theta$. But $\Delta$ is the product of $\Delta$ by $A$ from which
it follows that $\Lambda$ is the product of $\Delta$ by $\Theta$, so $\Lambda$
is equal to $X$. It is therefore clear that the product is in the proportion
and that its distance to the largest factor counts as many numbers as the
distance of the smaller factor to unity. But it is also clear that this
product is increased, from unity, by the sum minus one, of the distances
of the numbers $\Delta$ and $\Theta$ to unity; for $A,B,\Gamma, \Delta,
E, Z, H, \Theta$ are numbers among which $\Theta$ is increased?? from unity,
and $I,K, \Lambda$ are, up to one number, those from which $\Delta$ is
increased from unity; adding $\Theta$ one has the sum of the distances.
Chapter IV
The preceding being in part assummed and in part proved, I will now
prove my proposition. As we have assumed that the
diameter of a poppy--seed is not smaller than a fourtieth of a finger--breadth,
it is clear that the volume of the sphere having
diameter one finger--breadth does not exceed that of sixty four thousand
poppy--seeds; for this number indicates how many times it is the multiple
of the sphere having as diameter one fourtieth of a finger--breadth; it
has in fact been shown that spheres are related to each other as the cubes
of their diameters. As we have also assumed that the number of grains of
sand contained in one poppy--seed does not exceed a myriad, it is clear
that, if the sphere having diameter one finger--breadth were filled with
sand, the number of grains would not exceed sixty four thousand myriads.
But this number represents six units of second numbers increased by four
thousand myriad of first numbers, and is thus less than ten units of second
numbers. The sphere with diameter one hundred finger--breadths is equivalent
to one hundred myriad spheres of diameter one finger--breath, since spheres
are related to each other as the cubes of their diameters. If one now had
a sphere filled with sand of the size of the sphere of diameter one hundred
finger--breadths, it is clear that the number of grains of sand would be
less than the product of ten myriad second numbers and one hundred myriads.
But since ten units of second numbers make up the tenth number starting
from unity in the proportional sequence of constant ?? multiple ten, and
the one hundred myriads of the seventh number starting from unity in the
same proportional sequence, it is clear that the number obtained will be
the sixteenth starting from unity in the same proportional sequence. For
we have shown that the distance of this product to unity is equal to the
sum of, minus one, of the distance from unity of its two factors. From
these sixteen numbers the first eight are among, with unity, the numbers
called first numbers, the following eight are part of the second numbers,
and the last of these is one thousand myriad second numbers. It is now
evident that the number of grains of sand whose volume is equal to one
hundred finger--breadths is less than one thousand myriad second numbers.
Similarly, the volume of the sphere of diameter one myriad finger--breadths
is one hundred myriad times the volume of the sphere of diameter one hundred
finger--breadths. If one now had a sphere, filled with sand, of the size
of the sphere with diameter a myriad finger breadths, it is clear that
the number of grains of sand would be less than the product of one thousand
myriads of second numbers and one hundred myriads. But since one thousand
myriad second numbers are the sixteenth number starting from unity in the
proportional sequence and that one hundred myriad are the seventh number
starting from unity in the same proportional sequence, it is clear that
the product will be the twenty second number starting from unity in the
same proportional sequence. Of these twenty two numbers, the first eight,
with unity, are among the numbers called first numbers, the following eight
are among the numbers called second, and the six remaining numbers are
called third numbers, the last of which being ten myriad third numbers.
It is then clear that the number of grains of sand whose volume is equal
to a sphere of diameter of a myriad finger--breadths is less than ten myriads
of third numbers. And since the sphere with diameter one stade is smaller
than the sphere with diameter a myriad finger--breadths, it is also clear
that the number of grains of sand contained in a volume equal to a sphere
with diameter one stade is less than ten myriad third numbers. Similarly,
the volume of a sphere of diameter one hundred stadia is one hundred myriad
times the volume of a sphere of diameter one stade. If one now had a sphere,
filled with sand, of the size of the sphere with diameter one hundred stadia,
it is evident that the number of grains of sand would be less than the
product of ten myriad third numbers with one hundred myriad. And since
ten myriad third numbers are the twenty second numbers, starting from unity,
in the proportional sequence, and that one hundred myriad are the seventh
number starting from unity in the same proportional sequence, it is clear
that the product will be the twenty eighth number starting from unity in
the proportional sequence. Of these twenty eight numbers, the first eight,
with unity, are part of the numbers called first numbers, the following
eight are second numbers, the following eight are third numbers, and the
four remaining are called fourth, the last being one thousand units of
fourth numbers. It is then evident that the number of grains of sand whose
volume equals that of a sphere of diameter a hundred stadia is less than
one thousand units of fourth numbers. Similarly, the volume of a sphere
of diameter a myriad stadia is one hundred myriad times the volume of a
sphere having diameter one hundred stadia. If one then had a sphere, filled
with sand, of the size of a sphere of diameter a myriad stadia, it is clear
that the number of grains of sand would be less than the product of one
thousand units of fourth numbers with one hundred myriad. Just as one thousand
units of fourth numbers represent the twenty eighth number, starting from
unity, in the proportional sequence, and one hundred myriad the seventh
number in the proportional sequence, starting from unity, of the same proportional
sequence, it is clear that their product will be, in the same proportional
sequence, with unity, the thirty fourth number starting form unity. But
of these thirty four numbers, the first eight, with unity, are among those
numbers called first numbers, the following eight among second numbers,
the following eight among third numbers, the following eight among fourth
numbers, and the two remaining among fifth numbers, the last of these being
ten units of fifth numbers. It is thus clear that the number of grains
of sand whose volume is equal to that of a sphere having diameter a myriad
stadia will be smaller than ten units of fifth numbers. And similarly,
the volume of a sphere of diameter one hundred myriad stadia is one hundred
myriad times the volume of a sphere of diameter a myriad stadia. If one
had then had a sphere, filled with sand, of the size of the sphere with
diameter one hundred myriad stadia, it is clear that the number of grains
of sand would be smaller than the product of ten units of fifth numbers
and one hundred myriads. As the ten units of fifth numbers represent the
thirty fourth number starting from unity in the proportional sequence,
and one hundred myriads the seventh number starting from unity in the same
proportional sequence, it is clear that the product will be, in the same
proportional sequence, the fourtieth number starting from unity. But of
these fourty numbers, the first eight, with unity, are among the numbers
called first numbers, the eight following are second numbers, the eight
following are third numbers, the eight following are fourth numbers, the
eight following are fifth numbers, the last of these being one thousand
myriad fifth numbers. It is therefore clear that the number of grains of
sand whose volume is equal to that of a sphere of diameter one hundred
myriad stadia is less than one thousand myriad fifth numbers. But the volume
of a sphere of diameter a myriad myriad stadia is one hundred myriad times
the sphere of diameter one hundred myriad stadia. Thus, if one had a sphere,
filled with sand, of the size of a sphere of diameter a myriad myriad stadia,
it is clear that the number of grains of sand would be less than the product
of one thousand myriad fifth numbers by one hundred myriads. However, since
one thousand myriad fifth numbers represent the fourtieth number, starting
from unity, of the proportional sequence, and one hundred myriad the seventh
number starting from unity in the same proportional sequence, it is clear
that the product will be the fourty sixth number starting from unity. Of
these fourty six numbers, the first eight, with unity, are part of the
numbers called first numbers, the eight following second numbers, the eight
following third numbers, the eight following fourth numbers, the eight
following fifth numbers, and the six left over are numbers called sixth,
the last among being ten myriads of sixth numbers. It is thus clear that
the number of grains of sand whose volume is equal to a sphere of diameter
a myriad myriad stadia is smaller than ten myriad sixth numbers. But the
volume of a sphere of diameter one hundred myriad myriad stadia is one
hundred myriad times the multiple of a sphere of diameter a myriad myriad
stadia. Thus, if one had a sphere, filled with sand, of the size of a sphere
of diameter one hundred myriad myriad stadia, it is clear that the number
of grains of sand would be smaller than the product of ten myriad sixth
numbers by one hundred myriad. But, since ten myriad sixth numbers represent
the fourty sixth number, starting from unity, in the proportional sequence,
and one hundred myriad the seventh number starting from unity in the same
proportional sequence, it is clear that the product will be the fifty second
number starting in the same proportional sequence. But of these fifty two
numbers, the first fourty eight, with unity, belong to numbers called first
numbers, second numbers, third, fourth, fifth, and sixth, and the the four
remaining are among numbers called seventh numbers, the last of them being
one thousand units of seventh numbers. It is thus clear that the number
of grains of sand in a volume equal to a sphere whose volume is equal to
that of a sphere of diameter one hundred myriad myriad stadia is smaller
than one thousand units of seventh numbers.
As we shown that the diameter of the universe is less than one hundred myriad myriad stadia, it is clear that the number of grains of sand filling a volume equal to that of the universe is itself less than one thousand units of seventh numbers. We have thus shown that the number of grains of sand filling a volume equal to that of the universe, as the majority of astronomers understand it, is one thousand units of seventh numbers; we will now show that even the number of grains of sand filling a volume equal to the sphere as large as Artistarchus proposed for the fixed stars, is smaller than one thousand myriad eighth numbers. As we have assumed, in fact, that the ratio of the earth to what we commonly call the universe is equal to the ratio of this universe to the sphere of fixed stars as proposed by Aristarchus, the two spheres have the same ratio to each other. But it has been shown that that the diameter of the universe is less than a length a myriad times the multiple of the diameter of the earth. It is thus clear that the diameter of the sphere of fixed stars is itself smaller to a length a myriad times the diameter of the universe. But since the sphere have the ratio among themselves of their diameters, it is clear that the sphere of fixed stars, as Aristarchus proposes, is less than a volume a myriad myriad myriad times a multiple the volume of the universe. But we have shown that the number of grains of sand filling a volume equal to that of the world is less than a thousand units of seventh numbers; it is therefore evident that that if a sphere, as large as Aristarchus supposes that of the fixed stars to be, were to be filled with sand, the number of grains of sand would be less than the product of one thousand units [of seventh numbers] by a myriad myriad myriad. And since one thousand units of seventh numbers represent the fifty second number in the reciprocal sequence starting from unity, and a myriad myriad myriads the thirteenth number starting from unity in the same proportional sequence, it is clear that the product will be the sixty fourth number starting from unity in the same proportional sequence; but this number is the eighth of the eight numbers, which is one thousand myriads of eight numbers.
It is therefore obvious that the number of grains of sand filling a
sphere of the size that Aristarchus lends to the sphere of fixed
stars is less than one thousand myriad myriad eighth numbers.
I conceive, King Gelon, that among men who do not have experience of
mathematics, such a thing might appear incredible. On the other hand, those
who know of such matters and have thought about the distances and sizes
of the earth, the sun, the moon, and the universe in its entirety will
accept them due to my argument, and that is why I believed that you might
enjoy having brought it to your attention.