erstitious fears of death, of
supernatural beings, and of a future retribution.[782] The chief causes
of man's misery are his illusions, his superstitions, and his
prejudices. "That which principally contributes to trouble the spirit of
men, is the persuasion which they cherish that the stars are beings
imperishable and happy (_i.e.,_ that they are gods), and that then our
thoughts and actions are contrary to the will of those superior beings;
they also, being deluded by these fables, apprehend an eternity of
evils, they fear the insensibility of death, as though that could affect
them...." "The real freedom from this kind of trouble consists in being
emancipated from all these things."[783] And this emancipation is to be
secured by the study of philosophy--that is, of that philosophy which
explains every thing on natural or physical principles, and excludes all
supernatural powers.

[Footnote 782: Lucretius, "On the Nature of Things," bk. i. 1. 100-118.]

[Footnote 783: Epicurus to Herodotus, in Diogenes Laertius, "Lives of
the Philosophers," p. 453 (Bohn's edition).]

That ignorance which occasions man's misery is two-fold, (i.) _Ignorance
of the external world, which leads to superstition._ All unexplained
phenomena are ascribed to unseen, supernatural powers; often to
malignant powers, which take pleasure in tormenting man; sometimes to a
Supreme and Righteous Power, which rewards and punishes men for their
good or evil conduct. Hence a knowledge of Physics, particularly the
physics which Democritus taught, was needful to deliver men from false
hopes and false fears.[784] (ii.) _Ignorance of the nature of man, of
his faculties, powers, and the sources and limits of his knowledge_,
from whence arise illusions, prejudices, and errors. Hence the need of
Psychology to ascertain the real grounds of human knowledge, to explain
the origin of man's illusions, to exhibit the groundlessness of his
fears, and lead him to a just conception of the nature and end of his
existence.

[Footnote 784: "The study of physics contributes more than any thing
else to the tranquillity and happiness of life."--Diogenes Laertius,
"Lives," bk. x. ch. xxiv. "For thus it is that _fear_ restrains all men,
because they observe many things effected on the earth and in heaven, of
which effects they can by no means see the causes, and therefore think
that they are wrought by a _divine_ power. For which reasons, when we
have clearly seen that _not