THE ATOMIC THEORY OF LUCRETIUS.
. THE ?:
ATOMIC THEORY OF LUCRETIUS
CONTRASTED WITH MODERN DOCTRINES
OF ATOMS AND EVOLUTION.
JOHN MASSON, M. A.
GEORGE BEL L^ AND SONS,
YOKE STREET, COVENT GARDEN.
. The lense will not disprove
A present that eludes it ....
Though you saw the final atom-dance,
Making each molecule, that stands for sign
Of love, being present, where is still your love ?
CHISWICK PRESS: c. WHITVNGHAM AND co., TOOKS COURT,
IT is strange that the Greek atomic theory, of which
Lucretius is the sole exponent, has not, long before this,
been set in a clear and detailed form before the English
In Professor Veitch's little book ( f Lucretius and the
Atomic Theory,' 1875), only fifteen pages (pp. 10-25) deal
with Lucretius's theory of atoms, and that only in a general
way, while the rest of the volume is occupied with a very able
criticism of modern Materialism. The scope of Professor
Sellar's work does not allow him to enter at all minutely into
the science of Lucretius, though his chapter on the connecting
links between Lucretius's science and his poetry is most
valuable. 1 Zeller has indeed given us in his ( Pre-Socratic
Philosophy ' an admirable sketch of the system of Democritus,
but his account of the later development of the atomic theory
in the hands of Epicurus is by no means equally complete.
Lange's short chapters on Democritus, Epicurus, and Lucretius
in his ( History of Materialism ' contain acute enough criticism,
though in his statement of facts Lange is by no means so
trustworthy as Zeller. Neither Martha (' Le Poeme de Lucrece,'
1873} nor Guyau ('La Morale d'Epicure,' 1881) attempt to
give any complete or detailed account of the Epicurean theory
1 We may also refer to the interesting chapter of Professor Sellar's
* Virgil,' tracing the influence of Lucretius's leading doctrines on the
mind of the younger poet, and specially to the section on * The Lucretian
idea of Nature as it appears in the Georgics.'
of atoms, nor yet to point out its relations to modern science.
In the present volume we have attempted to supply a short
but careful account of the atomic theory as set forth by
Lucretius/ and to show how far each of his propositions is
in agreement with the conclusions of modern science, as repre-~
sented by Clerk-Maxwell, Tynflall, and others. We have
also endeavoured to point out the special vantage-ground
of Epicurean science, and to show why it was possible for
Epicurus's theory of the constitution of matter, as revived by
Gassendi and others, to become the basis of modern physics,
and to develop, stage by stage, into the atomic theory of
To Lucretius the existence of atoms as an unchangeable
basis of matter . is necessarily connected with the fact of de-
finite order and fixed laws in Nature. The crowning merit
of Epicurean science was, as we have shown, that at so early a
time it took so firm a hold of the principle of Law in Nature,
a fact grasped as firmly by Lucretius as it is by any modern
man of science.-
In modern scientific thought we find a parallel which helps
us . to realize how Lucretius's atomic theory taught him to
regard Nature, and how his conception of Matter developed
into a naive theory of Evolution. Recent inquiry and specula-
tion regarding the process of Evolution, the origin of Life and
the potency of Matter, as illustrated by Tyndall's famous
Presidential address, will enable us to realize more clearly,
by comparison, what Lucretius's actual belief on these points
In explaining Lucretius's theory of the atomic structure of
the soul, of the origin of consciousness, and of the method in
which Will sets the body in motion, attention is called, so far
1 See Dr. Brieger's review of our article in the ' British Quarter^,'
Oct., 1875, on * The Atomic Theory of Lucretius ' ( ' Jahresbericht liber die
Fortschritte der class. Alterthumswiss'., 1877, 2nd part, pp. 63-5).
as we know for the first time, to the subtle part which atomic
Declination plays in Epicurus's system. If it be thought tha*t
we have over-estimated the importance of this doctrine of
Declination, which is stated and discussed at length in Chapter
VII., 1 we may quote the opinion of M. Guyau, who calls it,
and we belieye justly, f the central and most original dccv
trine of Epicureanism.' 2 We have also pointed out the close
relation between this doctrine of Lucretius and Professor
Clifford's theory of ( Mind-Stuff.' The reasoning of both is
based on the same principle, and both apply it with equal
boldness. The question is an instructive one. In both cases,
Materialism, finding itself hard pressed, escapes as it were by a
back-door, and, in so doing, unconsciously confesses its own
powerlessness to account, unaided, for the origin ,of Life and
.M. Guyau devotes a long chapter of his very able work to
the doctrine of atomic Declination, which he explains as im-
plying a power of ( Spontaneity,' or modified Free-will action,
residing in all forms of Matter, and by its working producing
what we call Chance. He not only endeavours to prove that
this was the actual teaching of Epicurus, but even accepts
it as scientifically true. M. Guyau's theory of ( Spontaneity-
in-Things' is one of the most remarkable castles in the air
which the history of philosophy can show. We have examined
it at length in an additional chapter.
We have thus attempted to give some account of Lucretius's
position as regards both science and philosophy, and to indicate,
as impartially as we can^ both its strength and its weakness.
It is hoped that the following pages may contribute a little
1 In several papers we formerly attempted to indicate the philosophical
consequences implied in Declination (' British Quarterly,' Oct., 1875 ;
' Journal of Philology,' vol. xii., 1883 ; British Quarterly,' April, 1882).
2 'Le point capital et vraiment original de la thorie epicurienne '
(' La Morale d'Epicure,' 1881, p. 99).
towards a truer understanding of the Atomic Materialism of
feucretius, which forms none the less startling a chapter in
the history of human thought, that we see it repeating itself,
in somewhat subtler form, in the present day.
We must not forget to acknowledge, in common with all
who have endeavoured to master the philosophic system of
Lucretius, special indebtedness to Mr. Munro's edition. Much
as^Lachmann performed for the text, he left almost everything
undone for the explanation of the poem, a task of the utmost
difficulty. It required qualities of mind which are rarely
united to produce so trustworthy an edition as the great
English one. While presenting our own .rendering of the
passages quoted, we have to acknowledge the constant aid
derived from Mr. Munro's vigorous and admirably faithful
translation. We are also indebted to Professor Fleeming
Jenkin's thorough and original article on ( The Atomic Theory
of Lucretius' (' North British -Review,' vol. xlviii.), and have
often quoted from it in the second a*id third chapters.
What Science owes to the poem of Lucretius. Lucretius has
preserved for us the Atomic Theory of Epicurus . . . .1-6
Lucretius's First Proposition Law exists everywhere in Nature.
The atom of Lucretius and its properties. Atoms are of many
different shapes, but the number of these shapes is finite. Their
size. Reasoning by which Lucretius proves the existence of atoms.
Arguments of modern Chemistry for the existence of atoms. Parts
of the atoms. Anaxagoras's doctrine of the infinite divisibility of
Matter attacked by Lucretius. A Dissipation of Energy constantly
going on in the World. The World requires to be constantly fed
with fresh Matter. Balance of opposing forces in Nature. The
End of the World . . 7-33
Kinetics of the Atomic Theory. Are Lucretius's atoms elastic ?
The atoms of all solid bodies are in constant motion. In bodies
of different density the atoms rebound at greater or less intervals, w
Clerk-Maxwell on the motion of molecules in a gas or liquid.
Velocity of the atoms. Joule and Maxwell's calculations of the
velocity of molecules. Does 'concilium, imply some notion of
chemical affinity ? The doctrines of Emanations and of the inter-
penetration of Matter. Porousness of all bodies. The ' symmetry
of pores.' Gravitation. Atomic Declination and its object. The
velocity of the atoms remains always the same : in this doctrine
Lucretius anticipates the Conservation of Energy . . 34-55
Lucretius's formula of Evolution. He needs no protoplasm. v/
Difference of atomic structure is sufficient to account for the utmost v
X . CONTENTS.
difference in qualities of things, even for that between Matter and
Mind. The Birth of the World. Certain conditions implied in
Lucretius's theory of Matter help to explain the world's atomic
origin. Concilium. Tendency in the atoms to combination and
productiveness. The motion of infinite Matter in infinite time past
must at last eliminate the atoms fit to produce the world. Forma-
tion of earth and heaven. ' The Walls of the World.' Origin of Life
and Species. Survival of the Fittest. No Divine Mechanist outside >
the World. Lucretius allows no variation of species . . . 56-83
How modern Science attempts to bridge over the gulf left by
Lucretius between atoms and living things. The new Book of
Genesis. Tyndall, like Lucretius, sees in the world no trace of
Design. Matter contains the potency of every form of life. Three
points of Tyndall's argument : 'first, Mind does not exist apart
from Matter ; second, prolonging the line of Visjon leads to Spon- , ,
taneous Generation ; third, the Structural power of molecular Forces.
The formative power is within Matter. Tyndall refuses to believe '
in a Divine Mechanist acting on the world from without. Marti-
neau's criticism on all these points. Dr. Carpenter on the 'in-
herent potency ' of Matter. The relation of the World to God . 84-107
Epicurus's psychology.. The soul is spread all over the body. .
Its bulk, as compared with the body, is exceedingly minute. The
composition of the soul. The anima ad the animus. The fourth
substance which is ' the very soul of the soul ' : nothing else is
formed of such fine atoms : in this alone sensation and movement
originate. How our Will sets the body in motion : in every bodily
movement there is a gradual" increase of moving force, growing
. from- the very slightest initial impulse of Will in the soul-atoms.
The part played by Declination in Epicurean psychology. The
origin of Consciousness from dead atoms . . . / 108-22
The doctrine of Atomic Declination and the philosophical con-
sequences implied in it. Lucretius's reasoning in defence of the
doctrine analyzed. Nothing but Free-will in the atoms can deliver
CONTENTS. . XI
the mind of man from Necessity. Does this power exist in Matter,
yet produce no effect ? M. Guyau's theory. ' Carneades' argument
against Declination. Schopenhauer agrees with Epicurus in sup-
posing Will to exist in every form of Matter, and in associating
Will with the origin of Force. Lucretius's explanation of bodily
motion distinctly implies a power in the Will to originate Force.
His strong conviction of personal Free-will. Professor Clifford's
theory of ' Mind- Stuff'' runs closely parallel with the doctrine of
Atomic Declination'. Both doctrines boldly apply the same prin-
ciple, ex niJiilo niliil. In virtue of assigning Free-will to Matter
Lucretius is something more than a Materialist. . Lucretius's *,
Matter, which can of itself evolve Life, is Matter + Free-will . 123-42
The World as .conceived by Lucretius is practically to some
extent an Organism. How does the World 'hold its place in the
Universe? ' . * , .143-51
Lucretius's treatment of his subject. His method is genuinely
scientific. His illustrations. The 'De Rerum Natura' is the only
book of which the main subject-matter is Science, but which still
remains a Poem .... . 152-66
. CHAPTER X.
The Gods of Epicurus. Is Lucretius's conception of Nature as a
self-working Power necessarily inconsistent with Divine action ?
His antagonism to religion why ? Divination. The popular belief
in many Divine powers acting in nature was irreverent and de-
basing. Lucretius finally broke it down by preaching the realm of
Law. His mistrust of Nature. Sadness- of Lucretius's poem. In
spite of his Materialism he makes us feel that the world is divinely
beautiful, and something more than a dead machine. His intense
enthusiasm for humanity. The spiritual element in Lucretius's
teaching. The sacrifice of Iphigenia. Is Lucretius a mere enemy
of religion ? Where was Lucretius most to blame ? He realizes
Divine action only in the narrowest way as that of a man-like
artificer. He ignores the very possibility that God can be omni-
Xli . CONTENTS.
potent and all-wise. In truth, Lucretius prepared the way for
Theism. His gratitude to Epicurus. The personality and cha-
racter of Lucretius . . 167-206
AN EXAMINATION OF M. GuYAIl's CHAPTER ON ATOMIC DECLINA-
TION ('La Morale d'Epicure,' Paris, 1881). The doctrine of
* Sporitaneity-in- Nature ' which M. Guyau attributes to Epicurus.
His texts examined. Can ' Spontaneity ' exist in Nature side by
side with Law ? . . . . . .... . 209-33
I. The Atoms compared to manufactured articles * . . 2.37-38
II. Laws of Nature and Divine Premovement .... 238-41
S'lII. Shapes of the Atoms .241-42
IV., p. 128. Lucretius 's argument for Free-will (Book ii., 284-7).
Is there a difficulty in this passage ? Lucretius here sharply dis-
tinguishes between the world of Nature, governed by ' Necessity '
or Natural Law, and the mind of man, which is free . . . 243-46
V., p. 177. Lucretius's reasoning in ii. 251-93 has been gene-
rally misunderstood. Are the ' foedera natural ' opposed to the
'foedera fati'? Mr. Benn's assertion that Lucretius grasps only
the negative side of Natural Law . . . . . . 246-49
P. 5. 'In 1873 a well-known chemist.' By an oversight Professor
A. W. Williamson's name has been omitted.
P. 24. ' Two parts of hydrogen with one of oxygen,' ought to be
' Two parts ~by volume of hydrogen combine with one part by volume of
oxygen ' to form water. * Parts ' is now generally taken to signify parts
by weight. Two parts by weight of hydrogen combine with sixteen parts
by weight of oxygen to form water.
P. 69, note. * The facts of observation quoted by Lucretius in support
of this conclusion ' as to the actual size of the sun. See the remarks in
W. H. Mallock's ' Lucretius,' 1878, p. 38.
P. y.9. . In the quotation from Diog. L., ' The soul transmits sensation
to the body which is in union with it,' &c., ought to be ' The body ren-
ders sensation possible for the soul which is born with it, and the soul,
... by a faculty of its own, straightway realizes.' In note 1 on same page
add * Gassendi reads K(VI\VW for dvvr]<nv in this passage, and translates tlje
words Sid rrjs avvTfXeffQeiarjG Trepi awry ovvdp,e(i)g t per facultatem in ipso
collaboratam.' In first line of note read ^v%?), and in last line ovaa.
P. 123. Text of ii. 251-93. At 1. 257 potestas is the reading of Lach-
mann and Munro for voluptas of MSS. Lambinus transposes the last
word of 1. 258, and reads
unde est haec, inquam, fatis avolsa voluntas,
per quam progredimur quo ducit quemque voluptas.
THE ATOMIC THEORY OF LUCRETIUS.
THE ORIGIN OF THE ATOMIC THEORY.
OF late years the Roman poet Lucretius appears to have
acquired a very strong interest for scientific men and
others, and his name has found very frequent mention. This
unwonted popularity is not on account of his bold attempt to
abolish the gods and give a death-blow to superstition, hardly
caring, meanwhile, whether religion might perish at the same
time. Nor is he read by all even for his splendid poetic genius,
for some of his admirers are extremely unpoetic people. The
true reason is that his poem contains an admirably clear and
straightforward exposition of a scientific theory which is now
almost universally accepted, and which, in connection with
Evolution, has gained a new and somewhat startling impor-
tance. The propositions in which Lucretius has stated his
atomic theory anticipate some recent discoveries in both che-
mistry and physics in a most marvellous way. Science has now
proved that his propositions as to the constitution of matter,
in each case, are either certainly true, or else foreshadow
the truth. Thus Lucretius's exposition of the ancient atomic
theory has more than a mere historical interest, I^ndeejJ, its
agreement with the results of modern science makes us wonder
how the ancient students of nature, who had no means of veri-
fying the observations of the senses through experiment, could
2 THE ATOMIC THEOEY OF LUCEETIUS.
Lave succeeded as they did. Like men walking abroad at
night without a lantern, they couldjtake with them no test of
experimental inquiry by which to verify their hypotheses ; but,
in spite of-all, some faculty enabled thern to keep the right
path. And this is the more wonderful, because (like our modern
wave-theory of light and colour) the atomic hypothesis, in some
points, goes altogether contrary to the evidence of the senses.
Certainly, it must have been thought startlingly original when
first proposed, Hor is it easy to imagine what could have sug-
gested to any man's mind a conception which the senses seem
so to contradict. In these points it illustrates the fertile insight
of the Greek mind. Yet while we accept this theory as to the
constitution of matter as in very great part true, at the same
time we reject as completely false Lucretius's deduction from it,
the very thing for the sake of which he embraced it most
eagerly. To Lucretius the existence of . eternal uncreated
atoms is important specially because this enables him to prove
that the world has made itself, and that there is no room for
Divine action within it. 1
The poem on f Nature,' De Rerum Natura, has an extraneous
interest ; it is of value for more than the thoughts of Lucretius.
If Epicurus's great work, in thirty -seven books, entitled f Con-
cerning Nature,' or the other, 'Concerning the Atoms and
1 The late Clerk -Max well, so famous as an inquirer in the domain of
molecular physics, has even inferred from the character of the atoms, and
the exact collocation of matter which they exhibit, the existence of a first
cause, their Maker, from whom their powers are derived. Things which
are unalterable cannot, he argues, have been formed by any of the pro-
cesses which we call natural, and since each molecule is exactly similar
to all others of the same kind, they bear the character of * manufactured
articles,' not of that which is eternal and self-existent. But, according to
Professor Clifford, we have no evidence as yet that the molecules of any
given gas are * exactly ' of the same weight. Moreover, even if they were,
we have no evidence that it is absolutely impossible for molecules of
matter to have been evolved out of ether by natural processes (' The First
and the Last Catastrophe,' Essays and Eemains, vol. i.).
THE ORIGIN OF THE ATOMIC THEORY. 6
Void/ still existed, in which he set forth his theory of atoms,
we should go to him as the older and more original source.
Not that even he was its author : the germ of the theory is
attributed to Leucippus, whom Zeller considers to have been a
contemporary of Anaxagoras and Empedocles. It was next
taught by Democritus (sometimes called a pupil of Leucippus),
who died about B.C. 360, and it was nearly a century later
before it was fully developed by Epicurus. Zeller even says :
( It is certain that all the essential principles of the atomistic
physics^ felDDg_^_Li.iiJcippus,' x and that Democritus derived
thenvfrom him. 2 But Leucippus is only a name to us. Of De-
mocritus we know far more. To whatever extent he may have
accepted doctrines attributed to Leucippus, beyond question
Democritus deserves the credit of having originated the atomic
theory. 3 Democritus possessed a genuine scientific spirit. The
facts of his personal history, his many journeys for the sake of
acquiring knowledge and of observing nature, and his long life
of laborious research, show that, as Zeller says, f He was a man
who with rare devotion gave his life to science, and who, as it
is related, would have refused the kingdom of Persia in ex-
change for a single scientific discovery.' 4
There can be no doubt that the whole framework of Epicurus's
atomic theory and physics was built by Democritus, though in
1 * Pre-Socratic Philosophy,' vol. ii., p. 299 (Eng. Tr.).
2 ' The fundamental conceptions of the atomistic physics, which are
precisely those portions on which Lange lays so much stress, belong
therefore to Leucippus, whom he passes over so unaccountably in
silence.' ZELLER, ibid., vol. ii., p. 296 (Eng. Tr.).
3 We may here refer to the acute and able chapter on Democritus in
Lange's 'History of Materialism.' It however requires to be supple-
mented and corrected by Zeller's long section on Democritus, which is
full of the most careful and impartial research.
4 * The writings of Democritus which Sextus [who lived in the third
century, A.D.] still possessed were no longer in existence when Simpli-
kius wrote.' ZELLER, ibid., p. 215. The fragments of Democritus which
are preserved (Mullach, * Fragmenta Philosophorum Graecorum,' vol. i.)>
are mostly from his ethical writings.
4 THE ATOMIC THEORY OF LUCRETIUS.
not a few points of importance Epicurus corrected and greatly
expanded it. The atomic theory of Democritus was thoroughly
unpopular among both the philosophers and the natural in-
quirers 'of Greece. Most of them pass it by contemptuously.
Aristotle discusses it, but only to throw it aside. Therefore
Epicurus deserves credit not merely for having developed and
added to it, but also for the penetration which led him to revive,
and thus to preserve for the world a theory which in his own
day was generally scouted as absurd.
With the exception of a few letters and fragments of Epicurus,
the works of all three are lost to us, and this most astonishing
fruit of ancient thought, which has been adopted and substan-
tiated by modern experimental science, is to be found fully de-
scribed only in Lucretius's poem. Lucretius was born about
the end of B.C. 99, and died in B.C. 55, 1 at the age of forty-four.
His poem was written probably in the later years of his life.
He has followed Epicurus closely, as coincidences with the
fragments of Epicurus and the letters preserved by Diogenes,
make very plain. He has added perhaps nothing really new to
the theory : his contribution to it is only a most eloquent and
distinct exposition of what he found in Epicurus. There is good
reason for believing that but for this service done to it by
Lucretius, Epicurus's system would never have exercised the
powerful influence over modern thought which it has had.
Judging from the careless, slipshod style and general formless-
ness of Epicurus's surviving writings, Epicurus could never
have composed an account of his own doctrines, so clear and
distinct, yet so concise as that which Lucretius has left us. In
particular Lucretius's illustrations are admirable, so apt are they
in each case to the point which he is explaining. In the eyes
of science now, the value of Lucretius's poem lies in its full
and exact statement of the ancient atomic theory as held by
1 On the Ides of October, the same day on which Virgil attained the
age of fifteen.
THE ORIGIN OF THE ATOMIC THEORY. 5
Epicurus. This it is which at present gives Lucretius so
special an interest.
It was Gassendi who rescued Epicurus's atomic theory from
the forgotten science of the old world and revived it as the truest
basis for a scientific study of nature. Through Gassendi and
his influence both on Newton and on Boyle, 1 as well as on many
other minds in the 17th and 18th centuries, Epicurus's theory
has taken firm root in modern science, and has developed, by
stage after stage, into that atomic theory of modern chemistry
which has proved fruitful in so many fresh discoveries made
both in chemistry and, in our own day in particular, in mole-
cular physics. The history of the Atomic theory in recent
times is well known. The name of the chemist in whose hands