LEUCIPPUS AND DEMOCRITUS
But we must not leave this alluring field of speculation
as to the nature of matter without referring to
another scientific guess, which soon followed that of
Anaxagoras and was destined to gain even wider fame,
and which in modern times has been somewhat unjustly
held to eclipse the glory of the other achievement.
We mean, of course, the atomic theory of
Leucippus and Democritus. This theory reduced all
matter to primordial elements, called atoms
ατομα
because they are by hypothesis incapable of further
division. These atoms, making up the entire material
universe, are in this theory conceived as qualitatively
identical, differing from one another only
in size and perhaps in shape. The union of different-sized
atoms in endless combinations produces the
diverse substances with which our senses make us
familiar.
Before we pass to a consideration of this alluring
theory, and particularly to a comparison of it with
the theory of Anaxagoras, we must catch a glimpse
of the personality of the men to whom the theory
owes its origin. One of these, Leucippus, presents
so uncertain a figure as to be almost mythical. Indeed,
it was long questioned whether such a man
had actually lived, or whether be were not really an
invention of his alleged disciple, Democritus. Latter-
day scholarship, however, accepts him as a real
personage, though knowing scarcely more of him than
that he was the author of the famous theory with
which his name was associated. It is suggested that
he was a wanderer, like most philosophers of his
time, and that later in life he came to Abdera, in
Thrace, and through this circumstance became the
teacher of Democritus. This fable answers as well
as another. What we really know is that Democritus
himself, through whose writings and teachings
the atomic theory gained vogue, was born in Abdera,
about the year 460 B.C.—that is to say, just about
the time when his great precursor, Anaxagoras, was
migrating to Athens. Democritus, like most others
of the early Greek thinkers, lives in tradition as a picturesque
figure. It is vaguely reported that he travelled
for a time, perhaps in the East and in Egypt, and
that then he settled down to spend the remainder of his
life in Abdera. Whether or not he visited Athens in
the course of his wanderings we do not know. At
Abdera he was revered as a sage, but his influence upon
the practical civilization of the time was not marked.
He was pre-eminently a dreamer and a writer. Like
his confrères of the epoch, he entered all fields of
thought. He wrote voluminously, but, unfortunately,
his writings have, for the most part, perished. The
fables and traditions of a later day asserted that
Democritus had voluntarily put out his own eyes that he
might turn his thoughts inward with more concentration.
Doubtless this is fiction, yet, as usual with
such fictions, it contains a germ of truth; for we may
well suppose that the promulgator of the atomic
theory was a man whose mind was attracted by the
subtleties of thought rather than by the tangibilities
of observation. Yet the term "laughing philosopher,''
which seems to have been universally applied to
Democritus, suggests a mind not altogether withdrawn
from the world of practicalities.
So much for Democritus the man. Let us return
now to his theory of atoms. This theory, it must be
confessed, made no very great impression upon his
contemporaries. It found an expositor, a little later,
in the philosopher Epicurus, and later still the poet
Lucretius gave it popular expression. But it seemed
scarcely more than the dream of a philosopher or the
vagary of a poet until the day when modern science
began to penetrate the mysteries of matter. When,
finally, the researches of Dalton and his followers had
placed the atomic theory on a surer footing as the foundation
of modern chemistry, the ideas of the old laughing
philosopher of Abdera, which all along had been half
derisively remembered, were recalled with a new interest.
Now it appeared that these ideas had curiously
foreshadowed nineteenth-century knowledge. It appeared
that away back in the fifth century B.C. a man
had dreamed out a conception of the ultimate nature
of matter which had waited all these centuries for
corroboration. And now the historians of philosophy became
more than anxious to do justice to the memory
of Democritus.
It is possible that this effort at poetical restitution
has carried the enthusiast too far. There is, indeed, a
curious suggestiveness in the theory of Democritus;
there is philosophical allurement in his reduction of all
matter to a single element; it contains, it may be, not
merely a germ of the science of the nineteenth-century
chemistry, but perhaps the germs also of the yet
undeveloped chemistry of the twentieth century. Yet
we dare suggest that in their enthusiasm for the atomic
theory of Democritus the historians of our generation
have done something less than justice to that
philosopher's precursor, Anaxagoras. And one suspects
that the mere accident of a name has been
instrumental in producing this result. Democritus
called his primordial element an atom; Anaxagoras,
too, conceived a primordial element, but he called it
merely a seed or thing; he failed to christen it
distinctively. Modern science adopted the word atom and
gave it universal vogue. It owed a debt of gratitude
to Democritus for supplying it the word, but it somewhat
overpaid the debt in too closely linking the new
meaning of the word with its old original one. For,
let it be clearly understood, the Daltonian atom is not
precisely comparable with the atom of Democritus.
The atom, as Democritus conceived it, was monistic;
all atoms, according to this hypothesis, are of
the same substance; one atom differs from another
merely in size and shape, but not at all in quality.
But the Daltonian hypothesis conceived, and nearly
all the experimental efforts of the nineteenth century
seemed to prove, that there are numerous classes of
atoms, each differing in its very essence from the
others.
As the case stands to-day the chemist deals with
seventy-odd substances, which he calls elements.
Each one of these substances is, as he conceives it,
made up of elementary atoms having a unique personality,
each differing in quality from all the others.
As far as experiment has thus far safely carried us, the
atom of gold is a primordial element which remains an
atom of gold and nothing else, no matter with what
other atoms it is associated. So, too, of the atom
of silver, or zinc, or sodium—in short, of each and
every one of the seventy-odd elements. There are, indeed,
as we shall see, experiments that suggest the
dissolution of the atom—that suggest, in short, that the
Daltonian atom is misnamed, being a structure that
may, under certain conditions, be broken asunder.
But these experiments have, as yet, the warrant rather
of philosophy than of pure science, and to-day we demand
that the philosophy of science shall be the handmaid
of experiment.
When experiment shall have demonstrated that the
Daltonian atom is a compound, and that in truth there
is but a single true atom, which, combining with its
fellows perhaps in varying numbers and in different
special relations, produces the Daltonian atoms, then
the philosophical theory of monism will have the experimental
warrant which to-day it lacks; then we shall be
a step nearer to the atom of Democritus in one direction,
a step farther away in the other. We shall be
nearer, in that the conception of Democritus was, in a
sense, monistic; farther away, in that all the atoms of
Democritus, large and small alike, were considered as
permanently fixed in size. Democritus postulated
all his atoms as of the same substance, differing not at
all in quality; yet he was obliged to conceive that the
varying size of the atoms gave to them varying functions
which amounted to qualitative differences. He
might claim for his largest atom the same quality of
substance as for his smallest, but so long as he conceived
that the large atoms, when adjusted together to
form a tangible substance, formed a substance different
in quality from the substance which the small
atoms would make up when similarly grouped, this
concession amounts to the predication of difference of
quality between the atoms themselves. The entire
question reduces itself virtually to a quibble over the
word quality, So long as one atom conceived to be
primordial and indivisible is conceded to be of such
a nature as necessarily to produce a different impression
on our senses, when grouped with its fellows,
from the impression produced by other atoms when
similarly grouped, such primordial atoms do differ
among themselves in precisely the same way for all
practical purposes as do the primordial elements of
Anaxagoras.
The monistic conception towards which twentieth-century chemistry seems to be carrying us may perhaps
show that all the so-called atoms are compounded
of a single element. All the true atoms making up that
element may then properly be said to have the same
quality, but none the less will it remain true that the
combinations of that element that go to make up the
different Daltonian atoms differ from one another in
quality in precisely the same sense in which such tangible
substances as gold, and oxygen, and mercury, and
diamonds differ from one another. In the last analysis
of the monistic philosophy, there is but one substance
and one quality in the universe. In the widest view
of that philosophy, gold and oxygen and mercury and
diamonds are one substance, and, if you please, one
quality. But such refinements of analysis as this are
for the transcendental philosopher, and not for the
scientist. Whatever the allurement of such reasoning,
we must for the purpose of science let words have a
specific meaning, nor must we let a mere word-jugglery
blind us to the evidence of facts. That was the rock
on which Greek science foundered; it is the rock which
the modern helmsman sometimes finds it difficult to
avoid. And if we mistake not, this case of the atom of
Democritus is precisely a case in point. Because Democritus
said that his atoms did not differ in quality,
the modern philosopher has seen in his theory the essentials
of monism; has discovered in it not merely a
forecast of the chemistry of the nineteenth century,
but a forecast of the hypothetical chemistry of the
future. And, on the other hand, because Anaxagoras
predicted a different quality for his primordial elements,
the philosopher of our day has discredited the
primordial element of Anaxagoras.
Yet if our analysis does not lead us astray, the
theory of Democritus was not truly monistic; his indestructible
atoms, differing from one another in size
and shape, utterly incapable of being changed from
the form which they had maintained from the beginning,
were in reality as truly and primordially different
as are the primordial elements of Anaxagoras.
In other words, the atom of Democritus is nothing less
than the primordial seed of Anaxagoras, a little more
tangibly visualized and given a distinctive name.
Anaxagoras explicitly conceived his elements as
invisibly small, as infinite in number, and as made up of
an indefinite number of kinds—one for each distinctive
substance in the world. But precisely the same postulates
are made of the atom of Democritus. These
also are invisibly small; these also are infinite in number;
these also are made up of an indefinite number
of kinds, corresponding with the observed difference
of substances in the world. "Primitive seeds,'' or
"atoms,'' were alike conceived to be primordial,
unchangeable, and indestructible. Wherein then lies the
difference? We answer, chiefly in a name; almost
solely in the fact that Anaxagoras did not attempt to
postulate the physical properties of the elements beyond
stating that each has a distinctive personality,
while Democritus did attempt to postulate these properties.
He, too, admitted that each kind of element
has its distinctive personality, and he attempted to
visualize and describe the characteristics of the personality.
Thus while Anaxagoras tells us nothing of his elements
except that they differ from one another, Democritus
postulates a difference in size, imagines some
elements as heavier and some as lighter, and conceives
even that the elements may be provided with projecting
hooks, with the aid of which they link themselves
one with another. No one to-day takes these crude
visualizings seriously as to their details. The sole element
of truth which these dreamings contain, as distinguishing
them from the dreamings of Anaxagoras,
is in the conception that the various atoms differ
in size and weight. Here, indeed, is a vague fore-shadowing of that chemistry of form which began
to come into prominence towards the close of the
nineteenth century. To have forecast even dimly this
newest phase of chemical knowledge, across the abyss
of centuries, is indeed a feat to put Democritus in
the front rank of thinkers. But this estimate should
not blind us to the fact that the pre-vision of
Democritus was but a slight elaboration of a theory
which had its origin with another thinker. The association
between Anaxagoras and Democritus cannot
be directly traced, but it is an association which the
historian of ideas should never for a moment forget.
If we are not to be misled by mere word-jugglery, we
shall recognize the founder of the atomic theory of
matter in Anaxagoras; its expositors along slightly
different lines in Leucippus and Democritus; its re-discoverer of the nineteenth century in Dalton. All
in all, then, just as Anaxagoras preceded Democritus
in time, so must he take precedence over him also as
an inductive thinker, who carried the use of the scientific
imagination to its farthest reach.
An analysis of the theories of the two men leads to
somewhat the same conclusion that might be reached
from a comparison of their lives. Anaxagoras was a
sceptical, experimental scientist, gifted also with the
prophetic imagination. He reasoned always from the
particular to the general, after the manner of true induction,
and he scarcely took a step beyond the confines
of secure induction. True scientist that he was,
he could content himself with postulating different
qualities for his elements, without pretending to know
how these qualities could be defined. His elements
were by hypothesis invisible, hence he would not
attempt to visualize them. Democritus, on the other
hand, refused to recognize this barrier. Where he
could not know, he still did not hesitate to guess.
Just as he conceived his atom of a definite form with a
definite structure, even so he conceived that the atmosphere
about him was full of invisible spirits; he
accepted the current superstitions of his time. Like
the average Greeks of his day, he even believed in such
omens as those furnished by inspecting the entrails of a
fowl. These chance bits of biography are weather-vanes of the mind of Democritus. They tend to
substantiate our conviction that Democritus must rank
below Anaxagoras as a devotee of pure science. But,
after all, such comparisons and estimates as this are
utterly futile. The essential fact for us is that here,
in the fifth century before our era, we find put forward
the most penetrating guess as to the constitution of
matter that the history of ancient thought has to present
to us. In one direction, the avenue of progress
is barred; there will be no farther step that way till
we come down the centuries to the time of Dalton.