exceedingly diminutive, smooth, and round,
and connected with or diffused through the veins, viscera, and nerves.
The substance of the soul is not to be regarded as simple and
uncompounded; its constituent parts are _aura_, heat, and air. These are
not sufficient, however, even in the judgment of Epicurus, to account
for _sensation_; they are not adequate to generate sensible motives such
as revolve any thoughts in the mind. "A certain fourth nature, or
substance, must, therefore, necessarily be added to these, _that is
wholly without a name_; it is a substance, however, than which nothing
exists more active or more subtile, nor is any thing more essentially
composed of small and smooth elementary particles; and it is this
substance which first distributes sensible motions through the
members."[812]

[Footnote 811: As, _e.g._, Lucretius, "On the Nature of Things," bk.
iii. l. 260-290.]

[Footnote 812: Id., ib., bk. iii. l. 237-250.]

Epicurus is at great pains to prove that the soul is material; and it
can not be denied that he marshals his arguments with great skill.
Modern materialism may have added additional illustrations, but it has
contributed no new lines of proof. The weapons are borrowed from the old
arsenal, and they are not wielded with any greater skill than they were
by Epicurus himself, I. The soul and the body act and react upon each
other; and mutual reaction can only take place between substances of
similar nature. "Such effects can only be produced by _touch_, and touch
can not take place without _body_."[813] 2. The mind is produced
together with the body, it grows up along with it, and waxes old at the
same time with it.[814] 3. The mind is diseased along with the body, "it
loses its faculties by material causes, as intoxication, or by severe
blows; and is sometimes, by a heavy lethargy, borne down into a deep
eternal sleep."[815] 4. The mind, like the body, is healed by medicines,
which proves that it exists only as a mortal substance.[816] 5. The mind
does not always, and at the same time, continue _entire_ and
_unimpaired_, some faculties decay before the others, "the substance of
the soul is therefore divided." On all these grounds the soul must be
deemed mortal; it is dissolved along with the body, and has no conscious
existence after death.

[Footnote 813: Lucretius, "On the Nature of Things," bk. iii. l.
138-168.]

[Footnote 814: Id., ib., bk. iii. l. 444-460.]

[Footnote 815: Id., ib