THE MATERIALISTIC ATOMISTS: LEUCIPPUS AND DEMOCRITUS
SOURCES OF OUR INFORMATION
While the Atomic Theory is usually identified with the name of
Democritus, its real founder was Leucippus, as is attested by both
Aristotle (384-322 B. C.) and his successor, Theophrastus. Diogenes
Laertius, who flourished about 230 of our era, refers to Leucippus (De
Vitis, ix, 46) as the author of “The Great Diakosmos” (or “The Great
Order of the Universe”), in which were set forth the principles upon
which he based his atomic theory. A treatise “On the Mind” is also
mentioned, which appears to have contained in outline the psychology of
the materialistic Atomists.
Of the works of Leucippus there remains but one extant fragment, in
which Leucippus lays down in clear terms this universal rule: “Nothing
happens without a cause, but everything with a cause and by necessity”
(Aetius, Doxographers 321 B. 10).
Following in the footsteps of his master, Democritus also wrote a book
“On the Order of the Universe,” adhering, it would seem, very closely
to the views of Leucippus. The works of his master the great Milesian,
were incorporated eventually in the collected works of Democritus.
No writer, subsequent to Theophrastus (born at Lesbos about 390 B.
C., died in 286 B. C.), pupil of and successor to Aristotle as head
of the famous Lyceum at Athens, attempted to distinguish the teaching
of Leucippus from that of his more brilliant disciple. Zeller remarks
that “the work and even the name of Leucippus seems to have been pretty
early forgotten by most writers in comparison with the riper and more
exhaustive achievements of his disciple. The persistence with which he
is ignored by Epicurus, the reviver of the Atomistic philosophy, and by
most of the Epicureans, may have contributed to this.[6]
Of the once numerous writings of Democritus himself, only fragments
remain, but these are highly important. The chief collector of the
extant fragments was Mullach,[7] who places Democritus first on
the list of Greek philosophers for genius and knowledge, and thinks
it probable that the great Aristotle himself may owe much of his
reputation for learning to diligent perusal of the words of the sage of
Abdera. Says he: “(Democritus), although in other things dissimilar, in
his equal study of all the arts was most like the famous Aristotle. And
I scarcely know whether the Stagirite did not owe to his reading of the
works of Democritus his erudition, which surpassed that of all other
philosophers.”
Aristotle and some later historians make frequent references to his
teachings, and according to Zeller, “with respect.” Gompertz says that
Aristotle confers “a crown of eulogy” upon Democritus “at the expense
of Plato.”
Professor Lange remarks, however, that “he cites him, for the most
part, only when he attacks him, and this he by no means always does
with a fitting objectivity and fairness. How often he has borrowed from
him without naming him we do not know. Plato speaks of him nowhere,
though it is a matter of dispute whether, in some places, he has not
controverted his opinion without mention of his name” (“History of
Materialism,” page 18).
It seems to be quite possible that Plato knew little or nothing of
the writing of Democritus. At any rate, they were not well known
in Athens before Aristotle’s discussion of his theories. An extant
Democritean fragment states that “I went to Athens and no one knew me.”
Professor Burnet says: “It is not clear that Plato knew anything about
Democritus, for the few passages in the Timæus and elsewhere where he
seems to be reproducing him are easily explained by the Pythagorean
influences that affected them both. Aristotle, on the other hand, knows
Democritus well; for he too was an Ionian from the north.
“It is certain, nevertheless, that the Democritean corpus (which
included the works of Leucippus and others as well as those of
Democritus) continued to exist; for the school maintained itself at
Abdera and Teos down to Hellenistic times. It was therefore possible
for Thrasyllos in the reign of Tiberius to produce an edition of the
works of Democritus arranged in tetralogies just like his edition of
Plato’s dialogues. Even that did not suffice to preserve them.”[8]
Besides being the favorite pupil of Leucippus, Democritus (according
to Glaubus of Rhegion, a contemporary) had also Pythagoreans for
teachers, including the astronomer, geometrician and physician,
Philolaus, who was exiled from Italy in the first half of the fifth
century B. C. because of his membership in the Pythagorean Order.
Burnet thinks that this accounts not only for Democritus’ geometrical
knowledge but also “for other features of his system.”
THE PHYSICS OF DEMOCRITUS
We know that both Leucippus and Democritus regarded the atoms composing
the various substances of the world as being homogeneous--i.e., all
alike from a chemical stand-point, but differing from one another in
point of size and in rich variety of form. Unlike the minute particles
(homœomeries) of Anaxagoras, which were assumed to be infinitely
divisible as well as qualitatively different for each substance, the
atoms of Leucippus and Democritus were considered indivisible; hence
the name _atoma_ (atoms) (particles which cannot be cut, or
further divided).
But while the atoms are described as “indivisible,” because there is
no vacuum in them, this does not mean that they were regarded by
Leucippus and Democritus as mere mathematical points, like the atoms
of Boscovich[9] or the “point charges” (electrons) of some modern
physicists. They were bodies of a definite magnitude, some larger,
others smaller, but never of visible size (Sextus, _Mathematica_,
vii, 139), much less, as asserted by Stobæus (_Eclagarum physicarum
et ethicarum_, i, 348) “as large as a world.” According to
Simplicius (_Physica_, 18 a), Democritus taught that the atoms
were physically indivisible, but he did not claim that they were
_mathematically_ indivisible.
The variety of substances and organisms seen on every hand is due
entirely, according to Democritus--and also to Leucippus, whose views
are expressed by Democritus--to the infinite variety of the atoms
in form, size and _arrangement in space with reference to one
another_--an anticipation of modern stereochemistry (the arrangement
of the atoms of a molecule in space) and the work of van’t Hoff
(1852-1911).[10] In all other respects the atoms are alike, and act on
one another only by pressure or collision.
THE ATOMIC THEORY OF KNOWLEDGE
Man’s sense impressions--color, sound, bitterness, sweetness, etc.--are
merely the effect of the impact of atoms upon a particular grouping
or arrangement of physically varied but essentially (chemically)
homogeneous atoms, constituting our sense organs. Hence these sense
qualities have no existence in themselves--are mere deceptive
“appearances.” “Only in opinion consists sweetness, bitterness, cold,
color; in truth there is nothing but the atoms and empty space,” says
Democritus.
The great Protagoras (born about 500 B. C.), also of Abdera, a
contemporary of Leucippus and Democritus, had taught that all
sensations are equally true for the sentient subject--i.e., if a
substance tastes sweet to a given person, it is sweet. For Democritus
sweetness and bitterness did not reside as such in the substance
tasted, but were merely subjective effects produced on the palate
of the consumer. Taste is partly dependent upon the shape of the
atoms composing the food (they held) and partly upon the particular
taste-sense of the individual. Thus to the normal (or average) person
honey has a sweet taste, whereas the same honey to a jaundiced person
has a bitter taste.
Parmenides had already declared that taste, colors, sound and the like
were only names, standing for no objective qualities. Democritus agreed
that sensations _represent_ nothing external to ourselves, though
they are _caused_ by something outside us. For example, what we
call pungency, tartness, bitterness, saltiness, etc., were impressions
produced on the palate by atoms of a certain shape--sharp, rough,
pointed or hooked particles of matter producing an effect of pungency
or acidity. Atoms with smooth surfaces form substances which ordinarily
impress the senses agreeably. From this we learn the effect upon our
palates of certain substances, but these sensations tell us nothing of
the true nature of the substances tasted.
“By the senses,” says Democritus, “we in truth know nothing sure,
but only something that changes according to the disposition of the
body and of the things that enter into it or resist it” (Fragment 9).
True reality lies beyond sense impressions; “truth is in the depths”
(Fragment 11). Our ideas represent our impressions, and are not direct
reproductions of the external objects themselves, “the inner essence of
which is concealed from us.”
This ancient theory of the differences of taste depending on
differences in the shapes--or roughness or smoothness--of the particles
composing substances prevailed even well into the eighteenth century
of our own era; dictionaries of the period still defining acidity,
for example, as due to sharp, pointed particles. Today we still admit
that atoms are qualitatively homogeneous--but by “atoms” we now mean
electrons, the constituent electrical charges which make up the “atoms”
of the chemist. Differences in the number of electrons in atoms confer
upon them qualitative (chemical) differences, though all atoms of any
one element are chemically alike--are homogeneous. Differences in the
number of spatial arrangement of these atoms (in groups or “molecules”)
constitute both physical and chemical differences in substances, i.e.,
in compounds. Quite different substances are produced by combinations
of precisely the same _kinds_ of atoms, but in different
proportions.
Take from a molecule of certain substances one single atom, and they
may be changed from a compound necessary to life and growth into a
deadly poison. Phosphorus is an element, and thus contains but one kind
of atoms; but some (common) phosphorus is yellow and some (amorphous)
is red, varying with the spatial distribution of the atoms in the
molecules composing the phosphorus.
But the properties (or quality) of a compound are not merely the
_sum_ of the qualities of the different kinds of atoms composing
its molecules (a molecule being the smallest possible quantity of a
given substance or compound). Water, for example, is not merely the
addition of the qualities of one atom of oxygen to those of two atoms
of hydrogen (H₂O). It is something quite different from either of
these two elements. And just so the color of blue sulphate of copper
is not a mere mixture of the colors of sulphuric acid and copper.
Again, the experiments of Dr. P. W. Bridgman[11] showed that while
the application of ordinary pressures to ice causes it to melt, the
application of high pressures to water causes it to freeze, and that
“there are at least five different kinds of ice, only one of which we
are ordinarily familiar with” (Page 192). Paraffin, under pressures as
high as 20,000 atmospheres, “becomes more rigid than soft steel” (Page
188). Water, heretofore regarded as absolutely incompressible, was
found to decrease in volume about twenty per cent with a pressure under
12,000 atmospheres.
Professor W. T. Marvin could well say, in considering the shortcomings
of ancient atomic theories, that “even with our wealth of physical
information we cannot yet explain by a rigorous atomistic mechanics
water transforming into ice or a stick of wood burning, not to mention
the phenomena of living organisms.”
Modern science recognizes that not only different _results_
may be obtained under different conditions, but that _absolutely
new qualities_ emerge at critical moments, both in the domain of
chemistry and in the phenomena of biology. We talk now of _emergent
evolution_. “We live in a world in which there seems to be an
orderly sequence of events.... But the orderly sequence, historically
viewed, appears to present, from time to time, something genuinely
new.... If there be only regrouping of pre-existing events and nothing
more--then there is no emergent evolution.”[12]
In the gradual transition from non-living to living matter, an entirely
new and peculiar type of energy--“biotic energy” _emerges_, which
is not explicable merely on the grounds of increasing complexity of
atomic structure. “We call things _living_ because of the energy
changes they exhibit, and not because they are complex chemically
or physically.” A dead animal is just as _complex_ as a living
organism. What is missing is “biotic energy”--the form of energy
which gives rise to the distinctive energy-transformations “which we
aggregate together under the term _life_.” The recognition of
this fact, however, does not commit us to the outworn doctrine of
“vitalism” or to the Aristotelian “entelechy.”[13]
Leucippus and Democritus, of course, were not troubled with the
problems raised by such phenomena as we have just been considering,
since they knew nothing about them. For the founders of Atomism, a
multiplicity of substances, living matter, and consciousness could
readily be accounted for by the varied combination of variously formed
atoms, physically considered. What would be their astonishment to learn
that tens of thousands of different substances are actually composed
of only four kinds of atoms--viz., hydrogen, oxygen, nitrogen and
carbon! Yet for them _one_ element, qualitatively considered, was
sufficient to produce all that is--including the “soul”--provided this
primal matter existed in an infinite number of shapes and sizes of
atomic dimensions.
DEMOCRITEAN COLOR THEORY
“We have no exact information,” says Professor Gompertz, “as to
which bodies in the theory of Democritus were simple and which
were complex,” but he adduces evidences to show that “the infinite
multiplicity which Democritus recognized in the sizes and shapes of
atoms did not arise from his incompetence to perceive or to conjecture
a complex in an apparently simple body.”
He remarks that the Democritean theory of color started from the
assumption of four primary colors--white, black, red and green. “These,
with the exception of green, which had taken the place of yellow, were
likewise the primary colors in the scheme of Empedocles.” But all
other colors “were designated as _mixed_, and we see that all the
numerous bodies which were not equipped with one of the four primary
colors must have been of a composite nature. That is to say, they must
have included other than merely homogenously elementary particles....
The statements about the atomic forms underlying the several tastes
give rise at first impression (to the idea that) each of the countless
‘juices’ or materials of taste is composed of homogeneous atoms
possessing the size and shape required for the purpose.
“But this, we plainly perceive, was not the opinion of Democritus.
His own view of the mixed colors cries against it. The homogeneity
of the atoms was admissible in the case of white salt, but it was not
admissible in that of yellow-gold honey or of brownish-yellow human
bile. It is true that he must have referred the sweetness of the one
and the bitterness of the other to the presence of the atomic forms by
which these impressions were produced. But yellow and brown were mixed
colors in his theory, and he must accordingly have inferred that honey
and bile alike contained atoms of other forms as well.”
Professor Gompertz therefore concludes that “the true meaning of those
statements should therefore be expressed as follows: ‘In all substance
of mixed colors at least the kind of atoms which lends them their
specific taste is merely the predominant and preponderant kind, and
without wasting more words on this subject, Theophrastus, who is our
best authority for Democritus’ theory of sensation, relates that this
doctrine was expressly taught by him’.”[14]
FOOTNOTES:
[Footnote 6: Zeller, Dr. Edward, “Pre-Socratic Philosophy,” Vol I. Page
209, London, 1883. (English translation by S. F. Alleyne and O. J.
Reichel.)]
[Footnote 7: _Democriti Abderitae operum fragmenta_, Berlin, 1843.
Cf. Liepmann, Hugo Karl, “_Die Mechanik der leucipp-democrit’schen
Atome_,” Berlin, 1885; and Liard, _De Democrito philosopho_,
Paris, 1873; Lassewitz, “_Geschichte der Atomistik_,” Hamburg,
1890.]
[Footnote 8: “Greek Philosophy,” Vol. I, Pages 193-194, London, 1914.]
[Footnote 9: Boscoyish, Roger Joseph. _Theoria Philosophae
Naturalis_, etc., Vienna, 1758. A Latin-English edition of this work
has been issued from the press of the Open Court Publishing Company,
Chicago, 1923.]
[Footnote 10: Van’t Hoff was first to explain the cause of a known
difference in their behavior toward a beam of polarized light of
two distinct substances--both of which are called amyl alcohol--the
chemical formation of which is identical (i. e., composed of the same
number and kinds of atoms)--by a difference in the order in which
the four different groups of molecules are arranged in space about
the central carbon atom; the arrangements in the two cases being
such that one molecule has the same arrangement as the mirror image
of the other--equivalent to the difference between a right-hand and
a left-hand glove. Democritus could, possibly, on his theory, have
arrived at such an explanation; whereas Aristotle, on his theory of
the elements, could not possibly have done so--any more than could
Empedocles (495-436 B. C.) have done so with his “four elements.”
As for the primal substance (“air”) of Anaximines (588-54 B. C.)
and the “fire” of Heraclitus (535-475 B. C.), Dr. Gompertz contends
that these were implicitly recognized as being composed of “minute,
imperceptible particles” (“Greek Thinkers”, Vol. I, Page 323).]
[Footnote 11: “On the Properties of Matter under High Pressure.” Annual
Report of the Smithsonian Institution, 1918.]
[Footnote 12: Morgan, Professor C. Lloyd, “Emergent Evolution,” Pages
1-2, London, 1923. Cf. Mill, J. S., “Logic,” Book III, Chapter VI, ¶2;
Lewes, G. H., “Problems of Life and Mind,” Vol. II, Problem V, Chapter
III, Page 412.]
[Footnote 13: See on this point Moore, Dr. Benjamin, “Biochemistry--A
Study of the Origin, Reactions and Equilibria of Living Matter,”
especially Chapter IX, Pages 125-137, London, 1921.]
[Footnote 14: Gompertz, Opus citum, Pages 333-334. Authorized English
translation, from the German edition of 1896, by Laurie Magnus, M. A.
(Oxon.), London, 1906.]