it acquired a new force is now inseparably associated with it.
Dalton assumed the existence of atoms, conjectured that the
weight of the atoms making up each element is constant,
assigned different specific weights to the different kinds of
atoms, discovered the laws according to which they combine,
and thus founded his celebrated Atomic Theory.
were these discoveries and their results that Dalton has earned
the title of the ' Father of Modern Chemistry.' The progress
of chemical knowledge during the last century has been vitally
connected with the hypothesis that there are such things as
atoms, ultimate particles of matter, and its developments, nor
is its value, as concerns fresh discovery, yet exhausted// In
1873 a well-known chemist, the President of the British Asso-
ciation, asked, in the course of his address, ( What is the mean-
ing of the great activity shown at present in chemistry ? ' He
answered the question thus : ' Chemists are examining the
combining properties of atoms, and getting clearer views of
the constitution of matter.' Professor Huxley says, ( If there
is one thing clear about the progress of modern science, it is
the tendency to reduce all scientific problems, except those that
1 See the words of Boyle quoted by Lange, vol. i., p. 303.
6 THE ATOMIC THEORY OF LUCRETIUS.
are purely mathematical, to problems in molecular physics,
that is to say, to attractions, repulsions, motions and co-ordina-
tion of the ultimate particles of matter.' So important has
proved Epicurus's conception that there exist such ultimate
particles, molecules or atoms. Some of our readers may be
surprised to find how similar the atom, as described by
Lucretius, is to the modern chemical atom.
THE ATOM OF LUCRETIUS.
BEFORE beginning to set forth his philosophy in due
order, Lucretius expresses in the strongest way his
obligations to his master : e When human life lay shamefully
grovelling upon earth, crushed down under the weight of
Religion, who showed her face from heaven, frowning upon
mortals from on high with awful aspect, a man of Greece was
the first who ventured to lift mortal eyes to her face, and the
first to withstand her openly.' Neither stories of the gods nor
the thunders of heaven could make him afraid, but rather
spurred him on, says the poet, to burst the bars of nature and
find her secret. ( Therefore the living force of his soul pre-
vailed, and he passed out far beyond the flaming walls of the
world, 1 and traversed in mind the boundless universe, whence
he returns, a conqueror, to tell us what can be and what can-
not be ; in short, on what principle each thing has its proper-
ties defined and its deep-set boundary-mark. Wherefore
religion is put beneath our feet and trampled on in turn ; us his
victory raiSes to heaven. ,'
There is a boundless pity in the words describing the misery
1 What would Lucretius have said to the spectrum analysis, by which
the chemist can literally pass beyond the 'flaming walls of the world'
(that is, the fiery circuit of ether forming our heavens), and bring us
tidings from the distant stars ? Wonderful, indeed, he would have
thought it ; but he would have valued it most if it could have aided him
in any way to prove that the Gods have not created either the world or
man, and are powerless whether for good or evil.
8 THE ATOMIC THEORY OF LUCRETIUS.
of men from the dominion of superstition, the same pity and
enthusiasm for humanity that has made saints and philan-
thropists in all ages, from Saint Francis to Robert Owen
(though, certainly, there was more of the latter in the consti-
tution of Lucretius). But we have quoted the passage to show
what Epicurus was to Lucretius. Elsewhere he designates
him a god ; the popular deities, he says, are small compared
with him. It is characteristic of the poet that, believing in
no God whose help could avail mankind, he set up for worship
the best thing that he could find, a heroic man. But Lucre-
tius is far more in earnest than he whom he delights to call his
master. We cannot help questioning whether Epicurus would
have approved of Lucretius's fervour even in the way of
gratitude to himself. Was so great earnestness, even in the
cause of his own philosophy, consistent with the calm and
passionless tranquillity which the wise "should seek? This
passage, moreover, gives the keynote to the whole poem.
Probably nowhere does Lucretius forget that in his scientific
inquiries the highest interests of man are vitally concerned.
His demonstration of the existence of atoms is important
chiefly, he feels, in order that man may be enabled to live his
life aright, free from the crushing pressure of superstitious
fears. It is science for the sake of theology that is here treated.
The first two books contain a number of propositions as to
the qujdities of the atoms, exactly what is denominated in our
text-books the ( properties of matter.'
The first proposition is that f ^Lothing is ever begotten out of
nothing by ^Divine power.' This outset is science and theology
mingled, and it is, in this, characteristic of his whole work.
' Men see many phenomena take place in earth and heaven,
the causes of which they cannot understand, and, therefore,
believe them to be done by Divine power.' But I will show,
says Lucretius, how all things are done f without the hand of
the gods.' Fervently, and with submission, as Lucretius
THE ATOM OF LUCRETIUS.
v . . **t~ 1 *^ r
realized the order of nature, the notion of deities interfering
therewith must have seemed to him mean indeed. This, his
first principle, holds true invariably of matter once created, as
we daily observe it, and is assumed in every scientific treatise
of to-day. By it Lucretius means to express that the_laws. of
nature are constant, that phenomena take place according to
well-defined laws, and that nothing: happens without a cause
for it in na.tnrfi. His illustrations of the principle show that,
at any rate, he had distinctly grasped the fact of law as few,
or perhaps none, in his day can have done. If there is any-
thing for which the world is indebted to Epicurus (probably
still more to Lucretius), it is for a clear enunciation of the
principle of law in Nature. Lucretius asserts it over and over
again in modern-sounding phrases. ' It is absolutely decreed
ivhat each thing can do and what it cannot do, according to the
conditions of nature^ 71 Indeed, on this principle of the con-
1 These words are often, repeated in the poem and are intended to
carry a very weighty meaning. Lucretius first uses them at the very
outset of his task to express the triumphal and crowning result of
Epicurus's intrepid researches into nature, viz., the knowledge of natural
laws. It is this supreme discovery which, he tells us, finally delivers men
from their bondage to superstition
unde refert nobis victor quid possit oriri,
quid nequeat, finita potestas denique cuique
quanam sit ratione atque alte terminus haerens.
qua/re religio pedibus subiecta vicissim
opteritur, nos exaequat victoria coqlo. i. 75-79.
We may compare the passage where he sums up the aim of his poem
and, in order to do so, simply restates this one great principle, which he
has throughout been tracing and proving to hold good through the whole
cuius ego ingressus vestigia, dum rationes
persequor ac doceo dictis, quo quaeque creata
foedere sint, in eo quam sit durare necessum
nee validas valeant aevi rescindere leges. v. 55-58.
At the close of the paragraph he recapitulates the same principle,
quid queat esse,
quid nequeat, &c. v. 88-90.
10 THE ATOMIC THEORY OF LUCRETIUS.
stancy of law his whole philosophy is based. As we shall see,
Lucretius connects this principle of natural law with the inde-
A structibility of the atoms : were the atoms not unchangeable,
the productions of nature would not obey definite unchanging
laws. e For, if the fir^t_be^innings_p^in^s_c^uj^in_any way
be vanquished and changed, it would then be uncertain what
could ancTwhatf could' not^ come into being, _m_shgrt onjwhat
principle each thing has its properties fared, and its deep-set
Lucretius grasps this principle of law in
nature as strongly as does any modern man of science.
It need not be pointed out that this conception of the regu-
larity and orderly sequence of natural phenomena is the first
thing indispensable towards a scientific view of nature. But
Lucretius makes the same mistake on this point as many
modern scientific men, that, if anything is said to be done by
the hand of God, if, for example, He answers prayer, thereby
'a law is broken.' f lf, in consequence of prayer, external
nature can be affected,' says the man of science, ' natural laws
are thus at the mercy of man's volition, and no conclusion
founded on their permanence is worthy of our confidence.' 2
So, to Lucretius, definite physical laws and the hand of God,
acting in the world, seemed absolute contradictions. The
possibility of connecting lawsjwith aJDjvine power, with a God
who ( thinks them progressivelyforth,' \ seems never, even in
the faintest, rudest shape, to have occurred to Lucretius. His
only conception of Divine action is the polytheistic one of
1 i. 592-7. Lucretius is constantly using the word certus to describe the
fixity and uncJiangeableness of law, as manifested in the growth of natural
productions. See the passages quoted in our chapter on Guyau's ' La
Morale d'Epicure,' 3.
2 See Tyndall's essay on ' Prayer and Natural Law.' Tyndall's reason-
ing has been most searchingly examined by Dr. "W. Ward. Dr. Ward's
conception of a ' Divine pre-movement of events ' is by no means a novel
one, but he has worked it out with unusual force and grasp. We have
tried to give some notion of his argument in the Appendix.
THE ATOM OF LUCRETIUS. 11
interruption and Jnterference. Lucretius's attitude of mind in
regard to this forms a striking contrast to the instinctive God-
consciousness of the Hebrew race, to whom the regularity of
nature which we call law carried with it the inevitable inference
of a Divine Will manifesting itself in this orderly fashion. 1 To
Lucretius this regularity suggests just the opposite inference. ~~y
, Lucretius's second proposition, which completes the first, is ^ '
that e nothing is ever annihilated, but all things on their dis- *
solution go back into the first bodies,' that is to say, matter is.
imjjerishable^ and the total quantity of matter is never dimir
jmhd. 2 Lucretius closes his proof of the doctrine, after his
wont, by a picture of the working of this principle in nature.
' The rains die when father Ether has tumbled them into the
lap of mother Earth,' and in consequence the crops spring, the
trees are covered with leaves and with fruit, men and animals
are fed, the birds sing in the woods, the weak-limbed young of
the herd gambol on the grass, ' intoxicated with the pure new
milk,' and the children, human blossoms, make glad the city
hinc laetas urbes pueris florere videmus.
A picture of all that is most fresh and cheerful in the world.
The rains have passed away and out of sight, but they are not
lost. ' Therefore,' Lucretius concludes, f nothing that seems
to be lost is utterly lost, since nature makes one thing afresh
out of another, and suffers nothin
has been~recruited by the death of another.' The third pro-
1 Thus, to quote one example out of many, in Psalm cxlviii., of the
sun, moon, and stars, * He hath made them fast for ever and ever ; He hath
given them a law which shall not be broken.' This thought is expressed
in a very simple and natural way in Lord Houghton's beautiful little
poem, entitled ' Good Night and Good Morning.' A child is watching the
sun setting like a big red ball. She says ' Good Night ' to the objects round
her, and to the creatures all hastening to their homes, but not to the sun,
For she knew that he had God's time to keep
All over the world, and never could sleep.
2 i. 215-264.
12 THE ATOMIC THEORY OF LUCRETIUS.
-9 position states the existence of void. If there were no void,
motion would be perfectly impossible in a world perfectly
full of matter in its various forms, jammed together so that
you could not insert a pin's point anywhere. Again, f why do
we see one thing exceed another in weight, though it be no
larger in size ? ' Bodies of the same_bulk ought to weigh the
same, but do not. How can this be, unless the one has more
empty pores in it than the other^? Therefore, * void ' exists
^ mixed up with the substance of bodies.' Exactly this expla-
nation is at present given of the different specific gravity of
different substances. The third proposition states the existence
of void, but for which motion would be impossible. The next
two are, that all nature is made up of atoms and void, and that
nothing else but matter arid void exists.
The next proposition conducts us to the atom. ' Some
bodies,' says the poet, e are first-beginnings of things, the
remaining bodies are formed from a union (concilium) of first-
beginnings.' x These first-beginnings of things are the Lucre-
tian atoms. He also very often calls them f seeds ' or ' seeds
of things,' and ' bodies ' or e first bodies ; ' and sometimes ' first
principles ' (elementa), e shapes ' as they are conceived to differ
from each other in form, and ( matter ' as that from which
things are made. 2 Anticipating a little, we may here try
exactly to picture to ourselves an atom as Lucretius conceives
Corpora sunt porro partim primordia rerum,
partim concilio quae constant principiorum. i. 483-4.
2 According to Munro, Lucretius uses the following terms, primordia
or primordia rerum, which is his * proper and distinctive name for the
atoms ' ; semina or semina rerum or genitalia semina rerum, a phrase not
used by Epicurus, although Anaxagoras called his ultimate particles
< <T7rsp/Aara ; corpora (answering to o-w^ara, which Epicurus appropriated to
this special sense) or corpora prima ; elementa ; figurae (a phrase borrowed
from Democritus), and materies. On these terms and their Greek equiva-
lents, see Munro on i. 55. Zeller has pointed out that, amongst other
names for his atoms, Democritus uses aro/*a ('Pre-Socratic Philosophy,'
vol. ii., p. 219, 3, Eng. Tr.).
THE ATOM OF LUCRETIUS. 13
it. It is a little hard kernel, perfectly solid and indestructible.
f The first-beginnings of things no force can quench ; they are
sure to get the victory over it by their solid body.' Experience
can give us no notion of such solidity. Everything we see
around us in the world, however strong it may appear, iron,
stone, brass, is yet destructible. Reason alone forces us to ^J\
believe that the atoms are not. Ordinary bodies all have void
within them ; but first bodies are perfectly solid. Without
void ' nothing can be either crushed or broken up, or cut in
two ' (nee findi in bina secando ; Lucretius, who nowhere uses
the word atom, by these words exactly translates the Greek
Without void, a thing cannot admit within it the
destroyers, wet or cold or fire. Therefore the atoms, being
impenetrable and indivisible, are indestructible. Lucretius is
fond of calling them l strong in their solid singleness/
solida pollentia simplicitate. 1
i ( / '/ ' ' ' '
This is the most characteristic epithet which he gives them.
Each atom is a distinct, separate individual. Matter cannot
be divided farther, after you have reduced it to a collection of
these Individuals. ^Their * singleness ' that meaning their
distinctness of separate existence or individuality is their
strength. Though they enter into infinite fresh combinations,
' though stricken by countless blows through eternity,' they
cannot be worn away. They are as perfect and fresh to-day
as when the world was new. Each atom is perfectly hard,,
unchangeable and everlasting. (Of the more accessory pro-
perties of matter, it is proved that Lucretius assumes them to
As to the composition of this little kernel, though extremely
small, it yet has parts ; each^of those parts is ' of a leastjialure/
so small^that it never has existed separate by itself, and will at
1 i. 574. Again, at i. 612,
aeterna pollentia simplicitate.
14 THE ATOMIC THEORY OF LUCEETIUS.
no future time be able so to exist, since by its very nature it is
a part of the other. These parts appear to be quite identical
with one another. Each part is a minimum-. nothing^Gan-.be
smaller thanjhis and yet exist. These parts have existed from
eternity side by side in the atom ; 'in a close- wedged mass they
fill up the composition of the first body.' ( The first-beginnings
are not compounded from the union of those parts, but are to
be considered strong in everlasting singleness.' l Lucretius
appears to have thought three^the smallest number _ofj)arts
that an-aiom could have. Apparently he seems to have con-
ceived each ' part ' as representing an angle or corner/ so that
an atom with three parts would appear to be a three-cornered
or three-sided figure. The atoms differ in shape and size, and
consequently in_weigljt also, which must be in proportion to
their bulk. As to shape, the atoms are not every one of them
6 possessed of an equal size and like shape with one another.' 3
They differ widely in form. 4 Some aresmaller. ( The subtle
fire of lightning is formed of smallershapes,' and can pass
through openings better than ( this our fire, which' is born of
wood and sprung from pine.' Light is formed of smaller atoms
thjj/njthose of horn, and can therefore pass through it. Some
a/tomsjiave hooks, by which they are fastened together, and
come closer to each other. Hard things, like^ diamond, basalt,
iron, are formed of such atoms. ' Things which looF to us
primaque et una
inde aliae atque aliae similes ex ordine partes
agmine condense naturam corporis explent, ....
sunt igitur solida primordia simplicitate
quae minimis stipata cohaerent partibus arte,
non ex illarum conventu conciliata,
sed magis aeterna pollentia simplicitate. i. 604-612.
2 See Munro's note on 1. 600. Epicurus wrote a book " On the Angle
of the Atom ' Trtpi rrje lv ry drofiy yoma.
3 ii. 333-477.
4 fi ayKKTTpoeidfj, ?) TpiaivosiSfj, r) icpeieoacJj). Plutarch, ' De plac. ph.,' i., 3.
Is there any other authority for fr ring-shaped ' atoms ?
THE ATOM OF LUCRETIUS. 15
hard and close-textured must consist of atoms that are more
hooked together and must be held in union, because welded
together through and through out of atoms that are, as it were,
many-branched. Amid this class in the foremost line stand
diamond-stones, accustomed to despise blows, and stout basalt
blocks, 1 and the strength of hard iron, and the brass bolts
which scream out as they hold fast in the doors.' a Liquids,
are, as a rule, formed of smooth and round elements, buta
sluggish fluid, like oil, may have its atoms ( larger or more
hooked_an(L intertangled ' than those of wine. In general,
things which gratify the senses are formed of smooth and room d
atoms ; whatever is painful and harsh, its elements are more
hooked and rough. Again, ' some elements are with justice
thought to be neither smooth nor altogether hooked with
curved points, but rather to have very small angles slightly
projecting, so that they can rather tickle than hurt the senses. '
for example, tartar of wine and elecampane. Apparently
Lucretius supposes the different shapes of the atoms to result
altogether from the position in which the least parts are placed
within each. ' Every different arrangement of the parts yields
a different manner of form of the atom.' But there is a limit "*
to these differences: the number of shapes is finite, 3 but jhe
atoms of each shape are infinite in number. Lucretius argues
1 ' Silices denotes the hard blocks of volcanic basalt with which the
Eomans paved their streets and roads.' MUNKO.
Denique quae nobis durata ac spissa videntur,
haec magis hamatis inter sese esse necessest
et quasi ramosis alte compacta teneri.
in quo iam genere in primis adamantina saxa
prima acie constant, ictus contemn ere sueta,
et validi silices ac duri robora ferri
aeraque quae claustris restantia vociferantur. ii. 444-50.
3 ii. 478-494. In stating this, Lucretius supposes an atom formed of
three least parts, and adds that ' you may increase them by a few more.'
These words may be meant literally or not. It is calculated that from
three parts 6 different shapes might be derived, from four 24, from five
120, from six 720, from seven 5,040.
16 THE ATOMIC THEORY OF LUCRETIUS.
that there is not an infinitejiumber of differently shaped atoms,
for if so, some atoms must be infinitely large ; moreover^ som e
new kind of thing would be constantly coming into existence,
something- more brilliant, more beautiful, more fragrant, more
melodious, or the opposite, than any before-existing thing. 1
Epicurus held that the number of different shapes, though not
infinite, was inconceivably great. Lucretius merely proves
that it must be finite. All atoms of the same shape are not
necessarily of the same size. There are both greater and
smaller among atoms of the same shape. 2 Again, some round
atoms are smoother in surface than others also round. 3
As to size, we must keep well in mind that the atom, as
Lucretius conceived it, is a very tiny body. ( The whole nature of
the first-beginnings,' he says, ' lies far beneath the ken of sense.'
Early in the First Book he proves, by illustrations to which we
shall afterwards refer, that ' Nature works by bodies which are
invisible.' This is why he so often uses the epithet e blind,'
that is invisible, of the atoms and their movements. But he
insists emphatically that the atoms are not infinitely small.
Lucretius did to a certain extent try to realize the size of
his atoms. From his theory of sight, we see that he believed
theatoms to be exceedingly small, as compared with the
smallest visible objact. According to Epicurus, sight is caused
by a succession^ of images of any object striking jHLJtJia. eye.
1 ii. 478-521.
2 Thus Lucretius tells us that * the heavenly fire of lightning, subtle as
it is, is formed of smaller shapes, and therefore passes through openings
which this fire of ours cannot pass through, being born of logs and sprung
from pine' (ii. 384-7) these lines meaning that the atoms of fire are of
the same shape (that is, spherical) as those of lightning, but larger ; cf. vi.
225-7. The older atomists certainly held that atoms of the same shape
differ in bulk. Democritus held that fire is composed of small round
atoms. Theophrastus (* De Sensu,' c. 75) tells us that Democritus explained
red as produced by the juxtaposition of atoms similar to those of fire, but
larger, tpvOpbv d' t oionnrep TO 9epp,bv, TT\^V KK
3 ii. 469.
THE ATOM OF LUCRETIUS. 17
These ' images/ which are films so thin as to be utterly in-
tangible, are made of atoms, and are constantly streaming from
the surface of every object. * In a moment of time there must
be carried away from the surface of objects, images many in
number, in many ways, in all directions round.' x These films,
intensely thin, 2 never cease for a single moment to fly away
from every object, and the air is ever full of them, but they
are~ apparentronly to the eye, and the substances which send
them off show no trace of any loss ; how small, then, must be
the atoms forming such ( images.' Again, ' the mind perceives
much thinner images ' than the eyes can. 3 These images,
which are seen by the mind's eye, whether in thought or in
sleep, are infinitely finer even than those perceived by the eye,
yet these mental images, too, are atomic. How infinitely fine,
then, must be the atoms forming them ! Again, says Lucretius,
think of any very small living creature, and then of its entrails
or heart or eye. Exceedingly small such an organ must tie,
yet it is formed of a number of atoms. Further, the animal
life or soul of such an animalcule (according to Epicurean
psychology the soul of any creature is vastly finer and lighter
than its body), how almost inconceivably small, Lucretius
reminds us, must the soul of such a creature be in proportion
to its tiny body, yet its soul must be composed of many atoms. 4
sic ab rebus item siinili ratione necessest
temporis in puncto rerum simulacra ferantur
multa modis multis in cunctas undique partis. iv.. 163-5.
2 suptili praedita filo. iv. 88.
scire licet mentem simili ratione moveri,
per simulacra leonem et cetera quae videt aeque
nee minus atque oculi, nisi quod mage tenuia cernit. iv. 754-6.