ticles. And we do hear vaguely of physical particles in the
doctrine of Empedocles, but no definition is given of their
nature, and no clear conception is formed of their charac-
ter. Secondly, the moving forces of Empedocles, Love and
Hate, are fanciful and mythological. Lastly, though there
are in Empedocles traces of the doctrine that the qualities
of things depend on the position and arrangement of their
particles, this idea is not consistently developed. For Empe-
docles there are only four ultimate kinds of matter, qualita-
tively distinguished. The differential qualities of all other
kinds of matter must, therefore, be due to the mixing of
these four elements. Thus the qualities of the four elements
are ultimate and underived, but all other qualities must be
founded upon the position and arrangement of particles of
the four elements. This is the beginning of the mechani-
cal explanation of quality. But to develop this theory fully
and consistently, it should be shown, not merely that some
qualities are ultimate and some {88} derived from position
and arrangement of particles, but that all quality whatever
is founded upon position and arrangement. All becoming is
explained by Empedocles as the result of motion of material
particles. To bring this mechanical philosophy to its logical
conclusion, all qualitativeness of things must be explained
in the same way. Hence it was impossible that the philoso-
phy of mechanism and materialism should stand still in the
position in which Empedocles left it. It had to advance to
the position of Atomism. The Atomists, therefore, main-
tain the essential position of Empedocles, after eliminating
the inconsistencies which we have just noted. The philoso-
phy of Empedocles is therefore to be considered as merely
transitional in character.
First, the Atomists developed the theory of particles. Ac-
cording to Leucippus and Democritus, if matter were di-
vided far enough, we should ultimately come to indivisible
units. These indivisible units are called atoms, and atoms
are therefore the ultimate constituents of matter. They are
infinite in number, and are too small to be perceptible to
the senses. Empedocles had assumed four different kinds of
matter. But, for the Atomists, there is only one kind. All
the atoms are composed of exactly the same kind of matter.
With certain exceptions, which I will mention in a moment,
they possess no quality. They are entirely non-qualitative,
the only differences between them being differences of quan-
tity. They differ in size, some being larger, some smaller.
And they likewise differ in shape. Since the ultimate parti-
cles of things thus possess no quality, all the actual qualities
of objects must be due to the {89} arrangement and posi-
tion of the atoms. This is the logical development of the
tentative mechanism of Empedocles.I said that the atoms possess no qualities. They must,
however, be admitted to possess the quality of solidity, or
impenetrability, since they are defined as being indivisible.
Moreover it is a question whether the atoms of Democritus
and Leucippus were thought to possess weight, or whether
the weight of objects is to be explained, like other qualities,
by the position and movement of the atoms. There is no
doubt that the Epicureans of a later date considered the
atoms to have weight. The Epicureans took over the atom-
ism of Democritus and Leucippus, with few modifications,
and made it the basis of their own teaching. They ascribed
weight to the atoms, and the only question is whether this