are,
some triangular, some smooth and spherical, some are hooked with points.
They are also diversified in _magnitude_ and _density_. The number of
original forms is "incalculably varied," but not infinite. "Every
variety of forms contains an infinitude of atoms, but there is not, for
that reason, an infinitude of forms; it is only the number of them which
is beyond computation."[795] To assert that atoms are of every kind of
form, magnitude, and density, would be "to contradict the phenomena;
"for experience teaches us that objects have a finite magnitude, and
form necessarily supposes limitation.

[Footnote 795: Id., ib.]

A variety of these primordial forms enter into the composition of all
sensible objects, because sensible objects possess different qualities,
and these diversified qualities can only result from the combination of
different original forms. "The earth has, in itself, primary atoms from
which springs, rolling forth cool _water_, incessantly recruit the
immense sea; it has also atoms from which _fire_ arises.... Moreover,
the earth contains atoms from which it can raise up rich _corn_ and
cheerful _groves_ for the tribes of men...." So that "no object in
nature is constituted of one kind of elements, and whatever possesses in
itself must numerous powers and energies, thus demonstrates that it
contains more numerous kinds of primary particles,"[796] or primordial
"seeds of things."

"The atoms are in a continual state of _motion_" and "have moved with
_equal rapidity_ from all eternity, since it is evident the vacuum can
offer no resistance to the heaviest, any more than the lightest." The
primary and original movement of all atoms is _in straight lines, by
virtue of their own weight_. The vacuum separates all atoms one from
another, at greater or less distances, and they preserve their own
peculiar motion in the densest substances.[797]

[Footnote 796: Lucretius, "On the Nature of Things," bk. i. l. 582-600.]

[Footnote 797: Diogenes Laertius, "Lives of the Philosophers," bk. x.
ch. xxiv.; Lucretius, "On the Nature of Things," bk. i. l. 80-92.]

And now the grand crucial question arises--_How do atoms combine so as
to form concrete bodies?_ If they move in straight lines, and with equal
rapidity from all eternity, then they can never unite so as to form
concrete substances. They can only coalesce by deviating from a straight
line.[798] How are they made to deviate from a straight line? This
devi