., bk. iii. l. 438-490.]

[Footnote 816: Id., ib., bk. iii. l. 500-520.]

Such being the nature of the soul, inasmuch as it is material, all its
knowledge must be derived from sensation. The famous doctrine of
perception, as taught by Epicurus, is grounded upon this pre-supposition
that the soul is corporeal. "The eidola aporroiai--_imagines, simulacra
rerum, etc_., are, like pellicles, continually flying off from objects;
and these material 'likenesses,' diffusing themselves everywhere in the
air, are propelled to the perceptive organs." These images of things
coming in contact with the senses produce _sensation_ (aisthesis). A
sensation may be considered either as regards its object, or as regards
him who experiences it. As regards him who experiences it, it is simply
a passive affection, an agreeable or disagreeable feeling, passion, or
sentiment (to pathos). But along with sensation there is inseparably
associated some knowledge of the object which excites sensation; and it
is for this reason that Epicurus marked the intimate relation of these
two phenomena by giving them analogous names. Because the second
phenomenon is joined to the first, he calls it
epaisthesis--_perception_. It is sensation viewed especially in regard
to its object--_representative sensation_, or the "sensible idea" of
modern philosophy. It is from perception that we draw our general ideas
by a kind of prolepsis (prolepsis) an anticipation or laying hold by
reason of that which is implied in sensation. Now all sensations are
alike true in so far as they are sensations, and error arises from false
reasoning about the testimony of sense. All knowledge is purely relative
and contingent, and there is no such thing as necessary and absolute
truth.

The system of Epicurus is thus a system of pure materialism, but not a
system of materialism drawn, as a logical consequence, from a careful
and unprejudiced study of the whole phenomena of mind. His openly avowed
design is to deliver men from the fear of death, and rid them of all
apprehension of a future retribution. "Did men but know that there was a
fixed limit to their woes, they would be able, in some measure, to defy
the religious fictions and menaces of the poets; but now, since we must
fear eternal punishment at death, there is no mode, no means of
resisting them."[817] To emancipate men from "these terrors of the
mind," they must be taught "that the soul is mortal, and dissolves with
the body