10. The System of Materialism.
The systematic character of the doctrine of Democritus consists
in the way in which he carried through in all departments of his
work the fundamental thought, that scientific theory must so far
110 The Greeks : Systematic Period. [PART I.
gain knowledge of the true reality, i.e. of the atoms and their
motions in space, as to be able to explain from them the reality
which appears in phenomena, as this presents itself in perception.
There is every indication (even the titles of his books would show
this) that Democritus took up this task by means of investigations
covering the entire compass of the objects of experience, and in this
connection devoted himself with as great an interest to the psy
chological as to the physical problems. So much the more must we
regret that the greater part of his teachings has been lost, and
that what is preserved, in connection with accounts of others,
permits only a hypothetical reconstruction of the main conceptions
of his great work, a reconstruction which must always remain
defective and uncertain.
1. It must be assumed in the first place that Democritus was
fully conscious of this task of science, viz. that of explaining the
world of experience through conceptions of the true reality. That
which the Atomists regard as the Existent, viz. space and the par
ticles whirring in it, has no value except for theoretical purposes.
It is only thought in order to make intelligible what is perceived ;
but for this reason the problem is so to think the truly real that
it may explain the real which appears in phenomena, that at the
same time this latter reality may " remain preserved" 1 as some
thing that " is " in a derived sense, and that the truth which inheres
in it may remain recognised. Hence Democritus knew very well
that thought also must seek the truth in perception, and win it out
of perception. 2 His rationalism is far removed from being in con
tradiction with experience, or even from being strange to experience.
Thought has to infer from perception that by means of which the
latter is explained. The motive which lay at the foundation of
the mediating attempts following the Eleatic paradox of acosmism
became with Democritus the clearly recognised principle of meta
physics and natural science. Yet tmfortunately nothing is now
known as to how he carried out in detail the methodical relation
between the two modes of cognition, and how the process by which
knowledge grows out of perception in the particular instance was
thought by him.
More particularly, the theoretical explanation which Democritus
1 The very happy expression for this is duurdfciv TO. <t>a.Lvt>iteva. Cf. also Arist.
Gen. et Corr. I. 832, 5 a.
2 Hence, the expressions in which he recognised the truth in the phenome
non ; e.g. Arist. De An. I. 2, 404 a 27, and the like. To attempt, however, to
construe out of this a " sensualism" of Democritus, as has been attempted by
E. Johnson (Plauen, 1868), contradicts completely the accounts with regard to
his attitude toward Protagoras.
CHAP. 3, 10.] System of Materialism : Democritus. Ill
gave for the contents of perception consists, as with Leucippus, in
the reduction of all phenomena to the mechanics of atoms. What
appears in perception as qualitatively determined, and also as in
volved in qualitative change (dAAoiou/xe/xov), exists "in truth" only
as a quantitative relation of the atoms, of their order, and their
motion. The task of science is then to reduce all qualitative to
quantitative relations, and to show in detail what quantitative rela
tions of the absolute reality produce the qualitative characteristics
of the reality which appears in phenomena. Thus, the prejudice in
favour of what may be perceived or imaged (anschaulich), as if spatial
form and motion were something simpler, more comprehensible in
themselves, and less of a problem than qualitative character and
alteration, is made the principle for the theoretical explanation of
Since this principle is applied with complete systematic rigour
to the whole of experience, Atomism regards the psychical life with
all its essential elements and values as also a phenomenon, and the
form and motion of the atoms which constitute the true Being of
this phenomenon must be stated by the explanatory theory. Thus
matter in its form and motion is regarded as that which alone is
truly real, and the entire mental or spiritual life as the derived,
phenomenal reality. With this the system of Democritus first
assumes the character of conscious, outspoken materialism.
2. In the properly physical doctrines, the teaching of Democritus
presents, therefore, no change in principle as compared with that of
Leucippus, though there is a great enrichment by careful detailed
investigation. He emphasised still more sharply than his predeces
sor, where possible, the thought of the mechanical necessity (dvay*^
which he also occasionally called Aoyos), in accordance with which
all occurrence or change whatever takes place, and further defined
this thought as involving that no operation of atoms upon one
another is possible except through impact, through immediate con
tact, and further, that this operation consists only in the change of
the state of motion of the atoms which are also unchangeable as
regards their form.
The atom itself as that which " is," in the proper sense of the
word, has accordingly only the characteristics of abstract corpore
ality, viz. the filling of a limited space, and the quality of being
in motion in the void. Although all are imperceptibly small, they
yet exhibit an endless variety of forms (iSe cu or a-xrj^ra). To form,
which constitutes the proper fundamental difference in the atoms,
belongs in a certain sense also size ; yet it is to be observed that
the same stereometrical form, e.y. the sphere, may appear in different
112 The G-reeks : Systematic Period. [PART I.
sizes. The larger the atom, the greater its mass ; for the essential
quality of what is, is indeed materiality, space-claiming. For this
reason Democritus asserted weight or lightness to be a function of
size, 1 evidently yielding to the mechanical analogies of daily life.
In connection with these terms (fiapv and KOU<OV), however, we are
not to think of the falling motion, but solely of the degree of mechani
cal movability or of inertia. 2 Hence it was also his opinion that as
the atom-complexes whirled about, the lighter parts were forced out
ward, while the more inert with their inferior mobility were gath
ered in the middle.
The same properties communicate themselves as metaphysical
qualities to things which are composed of atoms. The form and
size of things is produced by the simple summation of the form and
size of the component atoms ; though in this case, the inertia is not
dependent solely upon the sum total of the magnitudes of the atoms,
but upon the greater or less amount of empty space that remains
between the individual particles when they are grouped together.
The inertia depends therefore upon the less or greater degree of
density. And since the ease with which particles may be displaced
with reference to one another depends upon this interruption of the
mass by empty space, the properties of hardness and softness belong
also to the true reality that is known by thought.
All other properties, however, belong to things not in them
selves, but only in so far as motions proceeding from things act
upon the organs of perception ; they are " states of perception as it
is in process of qualitative change." But these states are also
conditioned throughout by the things in which the perceived prop
erties appear, and here the arrangement and the situation which the
atoms have taken with reference to each other in the process of
composition are of principal importance. 3
While, then, form, size, inertia, density, and hardness are properties
of things eTefl, i.e. in truth, all that is perceived in them by the indi
vidual senses as colour, sound, smell, taste, exists only vo/x,o>or 0eW,
i.e. in the phenomenon. This doctrine, when taken up anew in the
philosophy of the Kenaissance (cf. Part IV. ch. 2) and later, was
1 As the most extensive exposition for this and for the following topic The-
ophr. De Sens. 61 ff. (Dox. D. 516) is to be compared.
2 It is scarcely to be decided now whether the motion of their own, which
Atomism ascribed to all the atoms as primitive and causeless, was thought of
by Democritus as conditioned already by the size or mass, so that the greater
had, even from the beginning, possessed less velocity. At all events, these
determinations held good for him within the sphere of the mechanical operation
of the atoms on one another. What is larger can be pushed with greater diffi
culty ; what is smaller can be pushed more easily.
Cf. Arist. Gen. et Corr. I. 2, 315 b 6.
CHAP. 3, 10.] System of Materialism : Democritus. 113
designated as distinguishing between the primary and secondary
qualities of things, and it is desirable to introduce this expression
here, since it corresponds throughout to the metaphysical and episte-
mological sense in which Democritus made the Frotagorean doctrine
useful for his own purpose. While the Sophist would make all
properties secondary and relative, Democritus admitted this only for
the qualities perceived by special senses, and set over against these
the quantitative determinations as primary and absolute. He there
fore designated also as " genuine knowledge " the insight into the
primary qualities to be won through thought, while, on the contrary,
perception which is directed toward the secondary qualities he
termed " obscure knowledge " (yvrjo-ir) O-KOTIT; yvw/i??)-
3. The secondary qualities appear accordingly as dependent
upon the primary ; they are not, however, dependent upon these
alone, but rather upon the action of these upon the percipient
agent. But in the atomistic system that which perceives, the mind
or soul, can consist only of atoms. To be more explicit, it consists,
according to Democritus, of the same atoms which constitute also
the essence of fire: namely, the finest, smoothest, and most mobile.
These are indeed scattered also through the whole world, and in so
far animals, plants, and other things may be regarded as animate, as
having souls, but they are united in largest numbers in the human
body, where in life a fire-atom is placed between every two atoms of
other sorts, and where they are held together by breathing.
Upon this presupposition, then, analogous, as we see, to the older
systems, Democritus built up his explanation of phenomena from
the true essence of things. That is, perception, and with it the
secondary qualities, arises from the action of things upon the fire-
atoms of the soul. The reality which appears is a necessary result
of the true reality.
In carrying out this doctrine Democritus took up and refined the
theories of perception advanced by his predecessors. The effluxes
(cf. above, 6, 3) which proceed from things to set in motion the
organs and through them the fire-atoms, he called images (a8o>A.a),
and regarded them as infinitely small copies of the things. Their
impression upon the fire-atoms is perception, and the similarity
between the content of this perception and its object was held to be
secured thereby. Since impact and pressure are the essence of all
the mechanics of the atoms, touch is regarded as the most primitive
sense. The special organs, on the contrary, were regarded as capable
of receiving only such images as corresponded to their own forma
tion and motion, and this theory of the specific energy of the sense
organs was worked out very acutely by Democritus. From this it
114 The G-reekis: Systematic Period. [?ART I.
followed also that in case there were things whose effluxes could
not act upon any one of the organs, these would remain imperceptible
for the ordinary man, and for these perhaps " other senses " might
This theory of images appeared very plausible to ancient thought.
It brought to definite expression, and indeed to a certain extent
explained, the mode of representing things which is still common
for the ordinary consciousness, as if our perceptions were " copies "
of things existing outside of us. If one did not ask further how
things should come to send out such miniature likenesses of them
selves into the world, he might think that he understood, by means
of this theory, how our " impressions " can resemble things with
out. For this reason this theory at once attained the predominance
in physiological psychology, and retained its position until after the
beginnings of modern philosophy, where it was defended by Locke.
Its significance, however, for the conceptions in the system of
Democritus, lies in this, that it was regarded as describing that
motion of the atoms in which perception consists. It remained
hidden from this materialism, which was such from principle, as
well as from all its later transformations, that perception as a
psychical activity is something specifically different from any and
every motion of atoms, however determined. But in seeking out
the individual forms of motion from which the individual percep
tions of the special senses arise, the philosopher of Abdera caused
many a keen observation, many a fine suggestion, to become known.
4. It is interesting now that the same fate befell the materialistic
psychology of Democritus as had befallen the pre-Sophistic meta
physicians (cf. 6) : it, too, was obliged in a certain respect to oblit
erate again the epistemological contrast between perception and
thought. Since, that is, all psychical life is regarded as motion of
the fire-atoms, 1 and since the motion of atoms in the connected sys
tem of the universe is conditioned by contact and impact, it follows
that thought, which knows the truly real, can be explained only from
an impression which this truly real makes upon the fiery atoms,
explained therefore itself only through the efflux of such images.
As a psychological process, therefore, thought is the same as percep
tion, viz. impression of images upon fire-atoms; the only difference
is that in the case of perception the relatively coarse images of the
atom-complexes are active, while thought, which apprehends true
reality, rests upon a contact of the fire-atoms with the finest images,
with those which represent the atomic structure of things.
i Arist. De An. I. 2, 405 a 8.
C HAP. ;5, lo.] System of Materialism : Democrifus. 115
Odd and fantastic as this sounds, the indications are yet all in
favour of the supposition that Democritus drew this conclusion from
the presuppositions of his m ierialistic psychology. This psychol
ogy knew no independent, internal mechanism of ideas or conscious
states, but only an arising of ideas through the motion of atoms.
Hence it regarded ideas that were evidently deceptive as also
" impressions," and sought for these the exciting images. Dreams,
e.g. were traced back to e?Sa>A.a. which had either penetrated into the
body in the waking state and on account of their weak motion had
previously produced no impression, or had first reached the fiery
atoms in sleep, evading the senses. A mysterious ("magnetic," or
" psychic," we should say to-day) action of men upon one another
appeared comprehensible on this hypothesis, and an objective basis
was given to faith in gods and demons by assuming giant forms in
infinite space from which corresponding images proceeded.
In correspondence with this Democritus seems to have thought of
" genuine knowledge " as that motion of the fire-atoms which is pro
duced by the impression of the smallest and finest images, those
which represent the atomic composition of things. This motion is,
however, the most delicate, the finest, the gentlest of all that which
comes nearest to rest. With this definition the contrast between per
ception and thought was expressed in quantitative terms quite in the
spirit of the system. The coarse images of things as wholes set the
fiery atoms into relatively violent motion and produce by this means
the "obscure insight " which presents itself as perception ; the finest
images, on the contrary, impress upon the fiery atoms a gentle, fine
motion which evokes the "genuine insight" into the atomic structure
of things, i.e. thought. In consideration of this, Democritus com
mends the thinker to turn away from the world of the senses, quite
in contrast with the mode of thought which would develop truth out
of perception. Those finest motions assert their influence only where
the coarser are kept back ; and where too violent motions of the
fiery atoms take place, the result is false ideation, the dAAo^poveiv. 1
5. This same quantitative contrast of strong and soft, violent
and gentle motion, was laid by Democritus at the basis of his ethical
theory also. 2 In so doing he stood with his psychology completely
upon the iutellectualistic standpoint of Socrates in so far as he
transposed the epistemological values of ideas immediately into
ethical values of states of will. As from perception only that
1 Theophr. De Sens. 58 (Dox. D. 515).
2 The resemblance with the theory of Aristippus ( 7, 9) is so striking, that
the assumption of a causal connection is scarcely to be avoided. Yet it may be
that we should seek for this rather in a common dependence upon Protagoras,
than in the interaction of Atomism and Hedonism upon each other.
116 The Greeks : Systematic Period. [PART I.
obscure insight follows which has for its object the phenomenon
and not the true essence, so also the pleasure which arises from the
excitation of the senses is only relative (VO/AW), obscure, uncertain
of itself, and deceitful. The true happiness, on the contrary, for
which the wise man lives "according to nature" (^uo-ei), the iv8unfj.o-
via, which is the end (TC XOS) and measure (ovpos) of human life, must
not be sought in external goods, in sensuous satisfaction, but only
in that gentle motion, that tranquil frame (tueo-rw), which attends
upon right insight, upon the gentle movement of the fiery atoms.
This insight alone gives to the soul measure arid harmony (V/A/AC-
rpia), guards it from emotional astonishment (aflau/xacna), lends it
security and imperturbability (drapa^ta, dtfa/x/fta), the ocean-calm
(yaXvyVr/) of the soul that has become master of its passions through
knowledge. True happiness is rest (lyo-uxia), and rest is secured only
by knowledge. Thus Democritus gains as the cap-stone of his
system his personal ideal of life, that of pure knowledge, free
from all wishes ; with this ideal, this systematic materialism cul
minates in a noble and lofty theory of life. And yet there is in it
also a tendency which characterises the morals of the age of the
Enlightenment : this peace of mind resting upon knowledge is the
happiness of an individual life, and where the ethical teachings of
Democritus extend beyond the individual, it is friendship, the rela
tion of individual personalities to one another, that he praises,
while he remains indifferent as regards connection with the state