3. The Atomic Theory. The devices by which
Democritus (ca. 460-367 B.C.) sought to resolve the
conflict between Heraclitean change (witnessed by the
senses) and Parmenidean permanence (required by
logical thought) were (1) the perpetuation of Par-
menides' distinction between appearance and reality,
but (2) the differentiation within reality of permanent
and immutable least parts of matter—“atoms”—on the
one hand, from their perpetual changes of place on
the other. All atoms were spatially extended, internally
homogeneous, qualityless, solid, rigid, and indivisible;
they differed in shape, size, characteristic positions in
relation to one another, and consequent velocities. If
there were many atoms of the same kind it was not
because nature came in species but because, given a
finite number of possible quantitative variations of an
infinite number of atoms, “chance” must run to dupli-
cations. The permanent actuality of the atoms was
postulated to avoid deriving being from non-being, but,
in defiance of Parmenides, the existence of non-being
was asserted in the form of the void to permit atomic
motion. Atom and void differed solely as the full (or
“well-kneaded”) from the empty, but this one real
distinction in the nature of things was the source of
all others and indeed of all qualitative determinations
found in sensory appearance. Time, for example, en-
joyed no such ontological status as space (or void), but
was the consequence of redistributions of full and
empty, “an appearance under the forms of day and
night” (Diels, 72). The impenetrability of matter, the
total penetrability of space, and their shared dimen-
sions determined natural processes with total and
mathematical necessity.
Phenomena were clearly radically in excess of what
the universe actually contained. Indeed Democritus
probably and his Epicurean followers certainly con-
ceived of philosophy precisely as an emancipation from
the deceptions of the senses and emotions. Thus super-
stitious fear was, characteristically, the product of an
overestimation of the capacity of the universe to inflict
pain. The cure was provided in the all-inclusive science
of the atom, the admittedly inferred but ultimately real
least part; sensory (and a fortiori imaginary) appear-
ance, by which “man is severed from the world” was
a sort of amalgam, or at least product, of the juxta-
position of the atom with its conceptual opposite, the
infinitely extended void. The theory, from its develop-
ment by Leucippus and Democritus, and populariza-
tion (cum modifications) by Epicurus and Lucretius has
since exercised an abiding attraction: on scientists be-
cause of the quantitative character of its model; on
humanist reformers because of its antisepsis of religious
beliefs and practices; and on all because of its simplic-
ity, clarity, and obvious correspondence to significant
mechanical aspects of macroscopic experience.
