Sources. Of the voluminous writings of Epicurus only a few
fragments have come down to us, and these are for the most part
unimportant. For the history of the school the most important primary
source is Lucretius' poem De Rerum Natura. As secondary sources
we have the works of Cicero, Plutarch, Diogenes Laertius, and the
History of the Epicurean School. Epicurus was born at
Samos in the year 341 or 342 B.C. His father, Neocles, was, Strabo
tells us, a school teacher. According to the tradition of the Epicurean
school, Epicurus was a self-taught philosopher, and this is confirmed
by his very superficial acquaintance with the philosophical systems of
his predecessors. Still, he must have had some instruction in
philosophy, for Pamphilus and Nausiphanes are mentioned as having been
his teachers; Epicurus, however, would not acknowledge his debt to
them, boasting that he had begun his self-instruction at the age of
fourteen, having been driven to rely on his own powers of thought by
the inability of his teacher to explain what was meant by the Chaos of
Hesiod. He first taught at Mitylene, afterwards at Lampsacus, and
finally at Athens, where he established his school in a garden, thereby
giving occasion for the name by which his followers were known, hoi
apo tôn kępôn. Here he taught until his death,
which took place in 270 B.C.
 For biographical data, cf. Ritter and Preller, op.
cit., pp. 373 ff.
The most celebrated of the disciples of Epicurus were Metrodorus
(born 330 B.C.), Hermarchus (who succeeded Epicurus as president
of the school and was succeeded by Polystratus),
Dionysius, and Basilides. Towards the end of the second
century B.C. the school was represented at Athens by Apollodorus, Zeno
of Sidon, and Phaedrus.
Amalfinius (about 150 B.C.) seems to have been the first to make
known the doctrines of Epicurus to the Romans. Later on we hear of a
Syro, or Sciro, who taught Epicurean philosophy at Rome; but it
is Lucretius (Titus Lucretius Carus, 95-51 B.C.) who, in his
poem De Rerum Natura, gives us the first Latin contribution to
Although the school of Epicurus is said to have been distinguished by
its cheerful tone, it is certain that it indulged in much abusive
criticism, for the Epicureans were known throughout antiquity as
leaders in the art of calumny. Everything, therefore, which the
Epicureans say about the systems and the philosophers of pre-Socratic
and Socratic times must have corroboration from other sources before it
can be accepted. Epicurus himself set the example in misrepresentation,
when he gave expression to his contempt for his teachers and
predecessors, while from his own followers he exacted every outward
mark of respect, even insisting on their committing to memory certain
brief formulas (,~pw.t &$iu) which contained the pith of his
teaching.  Hence it is that the Epicurean philosophy adhered so
closely to the form which it first received from the teaching of
 Cicero, De Fin., II, 7.
Epicurean Notion of Philosophy. Having defined philosophy as
the art of making life happy,  and having laid down the
principle that there should be no deviation from the kuriai
doxai, Epicurus subordinated speculation to the practical aspects
of philosophy and effectively discouraged all independence of thought
on the part of his disciples. It is well known that he despised
learning and culture. The only logical problem to which he gave even
cursory attention was the problem of knowledge. He attached greater
value to the study of nature, but only because he considered that a
knowledge of natural causes may free the mind from a fear of the gods
and in this way contribute to human happiness.  In the philosophy of
Epicurus, therefore, ethics, or the inquiry into the nature and
conditions of happiness, is the paramount problem, to which
logic and the study of nature are merely the
 Sext., Mathem., XI, 169.
 Cicero, De Fin., I, 7.
Epicurean Logic. This portion of Epicurean philosophy was styled
canonic, because it consists merely of a system of rules,
or canons, referring to the acquisition of knowledge and the
ascertainment of truth. It passes by the questions of formal logic and
is in reality an epistemology.
In their theory of knowledge the Epicureans favor a more
pronounced sensism than that of the Stoics. They maintain that, while
in practice the standard of truth is pleasure and pain, in theory the
ultimate test of all knowledge is sensation
(aisthêsis). Sensation as such, is always to be relied
upon; error lies not in the sensation itself, but rather in our
judgment concerning sensation. Several sensations amalgamated in a
general picture result in a notion (prolêpsis). The
notion, however, as regards objective value, is not superior to the
sensations from which it arises.  From notions arises opinion,
or thought (doxa, hupolêpsis), which likewise
depends on sensation for its truth.
 Diog. Laer., X, 33.
How, then, does sensation take place? In their answer to this question
the Epicureans content themselves with reproducing the doctrine of
Democritus, according to whom sensation takes place by means of certain
effluxes (eidola, aporroai), which, detaching themselves
from external objects and passing through the pores of the air, enter
the senses. If, therefore, sensation is sometimes apparently at fault,
the real source of the deception lies in the objective distortion or
mutilation of the efflux-images. Thus, for example, the image of a man
and the image of a horse, combined as it were by accident, give rise to
the impression of a centaur. Our impression, even in cases of this
kind, corresponds to the image, and consequently the sensation is true.
And if, as sometimes happens, the same object affects several persons
differently, the cause of the diversity of impression is the plurality
of images; the sensation in each case is true because it corresponds to
the image which produces it.
 Lucr., IV, 26. References are to the poem De Rerum Natura.
 Op. cit., IV, 730.
 Cf. Zeller, op. cit., p. 432.
Epicurean Physics. The physical doctrines of the Epicureans
receive their tone and character from the purpose which the Epicureans
always had in mind throughout their investigations of nature, -- to
free men from the fear of the gods. To this aim the Epicureans
subordinated their physical inquiries, and as they cared little whether
their explanation was accurate or inaccurate, complete or incomplete,
they left matters of detail to be settled by individuals according to
individual choice, insisting, however, in their general explanation of
natural phenomena, on the exclusion of any cause that was not a natural
Deliberately rejecting the Socratic philosophy of nature and turning to
the pre-Socratic systems of philosophy, Epicurus recognized that the
philosophy which was most naturalistic in its explanations and waged
most persistent warfare on final causes, was that of Democritus. As his
theory of nature, therefore, he adopted the physics of Democritus,
modifying it, as we shall see, in one important respect. Thus he
accepted without modification the atomism of Democritus as well
as the Democritean idea of a vacuum. Nothing exists except atoms
and void: mind as moving cause is a superfluous postulate:
Ergo, praeter inane et corpora, tertia per se
Nulla potest rerum in numero natura relinqui. 
 Lucr., I, 445.
The only point on which Democritus and Epicurus differ is in reference
to the primal motion of atoms. Democritus maintained that the
atoms, falling through empty space, moved with different velocities on
account of their difference in weight. This, Aristotle pointed out, is
impossible. Epicurus, acknowledging the justice of Aristotle's
criticism, sought to account for the collision of the falling atoms by
postulating on the part of the atoms a self-determining power by
means of which some
of them swerved slightly from the vertical line and thus  caused a
circular or rotatory motion.
 Lucr., II, 216.
In his account of the origin of life Epicurus accepted the
theory of Empedocles, who held that all sorts of deformed and
monstrous creatures first sprang from the earth, those alone surviving
which were fit to support and protect themselves and to propagate their
The Epicurean account of human society is well known. Lucretius 
taught that the men of olden times were as strong and as savage as
beasts; that the primitive condition of the race was one of warfare;
and that civil society was formed as a protection against anarchy and
the absolute power of kings.
 V, 925 ff.
Similarly, religion, according to the Epicureans, was of natural
growth. Fear is the basis of religion. Ignorance, too,
is a factor in the genesis of the religious instinct. It was owing to
ignorance and fear that men attributed natural portents to the
intervention of supernatural powers and sought to explain the
regularity of the motion of the heavenly bodies by referring it to the
agency of Providence. Nevertheless, Epicurus did not wholly abandon
belief in the gods. The gods, he said, exist because they have appeared
to men and left on the minds of men representative images
(prolępseis).  They are immortal; they enjoy perfect
happiness; formed of the finest atoms, they dwell in the uppermost
parts of the universe, in the spaces between the stars. The popular
notion, however, that the gods take an interest in human affairs is
erroneous, because an interest in the affairs of men would be
inconsistent with the perfect happiness which the gods enjoy. 
 Lucr., III, 14; I, 62.
 Cf. Cicero, De Nat. Deorum, I, 16.
 Diog. Laer., X, 123.
The human soul is, like the gods, composed of the finer kind
of atoms. It is a more subtle kind of body, resembling air and
fire.  More accurately, it is composed of air, fire, vapor, and
a fourth element, which is nameless. This last constitutes the
rational part (logicon) of the soul, which is seated in the
breast, while air, fire, and vapor constitute the irrational part,
which is scattered throughout the remainder of the body. Lucretius
calls the rational part animus, or mens, and the
irrational part anima. 
 Op. cit., X, 63.
 Cf. III, 94 ff.
According to the Stoics, it is the soul which holds the body together;
according to the Epicureans, it is the body which shelters the atoms of
the soul, so that, when the protection afforded by the body ceases, as
it does at the moment of death, the soul atoms are instantly
scattered, owing to their extreme lightness.  In this way Epicurus,
keeping in mind the chief aim of all his physical inquiries, sought to
rob death of its terrors by teaching that there is no future
life. "Tota res ficta est pueriliter," as Cicero exclaims.
 Lucr., III, 417 ff.
Epicurus asserted the freedom of the will. He denied the existence of
fate, but in his own analysis of human action he was obliged to
substitute chance for fate. Despite his doctrine of freedom, he was
forced to maintain that there is no truth in disjunctive propositions
referring to the future. 
 Cf. Cicero, De Nat. Deorum, I, 25.
Epicurean Ethics. The Epicurean canonic and the general views
which the Epicureans maintained in matters of physical science led
inevitably to the conclusion that the only unconditional good is
pleasure, a conclusion which is the basis of Epicurean ethics. The
ethical system of Epicurus is simply a modified form of the Hedonism of
Aristippus and the other Cyrenaics. When, however, Epicurus comes to
define pleasure, he does not, like Aristippus, define it as a gentle
motion: considering rather its negative aspect, he describes it as the
absence of pain. He does not indeed omit the positive aspect; he merely
insists that the negative aspect, repose of mind (ataraxia), is
essential, while the gentle motion which constitutes positive
pleasure is secoridary and accidental.  Unsatisfied desire is pain,
and pain is destructive of mental repose; for this reason, and for this
reason alone, should the desires be satisfied, and it is only in this
way that positive pleasure becomes part of the highest good. 
 Diog. Laer., X, 136.
 Seneca, Ep. 66.
The difference between the Epicureans and the Cyrenaics is furthermore
apparent in the Epicurean doctrine of the hierarchy of pleasures.
Highest of all pleasures are those of the mind, namely, knowledge and
intelligence, which free the soul from prejudice and fear, and
contribute to its repose. For this reason the wise man should not place
his hope of happiness in the pleasures of sense, but should rise to the
plane of intellectual enjoyment. Here, however, Epicurus was
inconsistent; he could not logically maintain a distinction between
sense and intellect. Indeed, Diogenes  preserves a saying of Epicurus
to the effect that there is no good apart from the pleasures of the
senses, and Plutarch and others represent Metrodorus as maintaining
that everything good has reference to the stomach. 
 X, 6.
 Cf. Ritter and Preller, op. cit., 387.
In their application of the doctrine of pleasure the Epicureans recognize
that each man is, in a certain sense, his own legislator. It is for him
to determine what is useful or pleasant and what is harmful or painful.
Hence the principle of moderation: Restrain your needs and desires
within the measure in which you will be able to satisfy them. And,
while no kind of pleasure is evil in itself, the wise man will avoid
those pleasures which disturb his peace of mind and which, therefore,
entail pain. 
Virtue has for the Epicureans a merely relative value. It is not
good or praiseworthy in itself, but only so far as it is useful in
securing that painlessness which is the happiness of life. The virtuous
man secures the maximum of pleasure and
the minimum of pain; temperance teaches him to avoid excess,
and courage enables him to forego a pleasure or endure a pain
for the sake of greater pleasure or less pain in the future. Less
successful even than these attempts at finding a rational basis for
courage and temperance is the Epicurean attempt at analyzing the virtue
of justice; for justice in the Epicurean philosophy is based on
the social compact into which primitive man entered as a means of
self-defense and self-preservation. Cicero complains that the ethics
of the Epicureans leaves no place for the sentiment of honor; a more
serious fault is its failure to supply a rational basis for the virtue
The claims which the Epicureans advanced on behalf of the wise man are
similar to those advanced by the Stoics. The wise man alone is master
of his desires; he is unerring in his convictions; he is happy in every
circumstance and condition of life; and although he is not, as was the
Stoic sage, wholly unemotional, still he holds his emotions in perfect
control. Later, however, this ideal gradually degenerated, and despite
the example of moderation set by Epicurus and his early followers, the
wise man of Epicurean tradition became the model of the careless man of
the world, with whom it is impossible to associate earnestness of moral
Historical Position. The Stoic and the Epicurean schools, the
two most important schools of the period, both sprang up and developed
under the influence of the same external conditions. The internal
principle of their development was, however, different. The Stoics
were fatalists; the Epicureans were casualists. This difference in
their conception of nature led to the difference in their view of
practical life which is so apparent in their ethical systems. Yet there
were points, theoretical as well as ethical, in which the two schools
approached very close to each other. Both were materialistic in their
physical systems and sensualistic in their theories of knowledge; both
were illogical in their development of the idea of duty, although,
as Zeller points out, the charge of inconsistency is urged with less
justice against the Epicureans than against the Stoics. The Epicureans
defined philosophy as the art of making life happy, and for them
happiness was primarily a matter of feeling rather than of knowledge,
while the Stoics defined happiness as consisting in a life led in
harmony with nature. For the Stoic, therefore, the study of nature and
the adoption of a consistent theory of nature were of greater
importance than they were for the Epicurean.
The physics of the Epicureans differs, as has been said, from the
physics of Democritus in regard to the doctrine of the swerving motion
of the atoms, -- an admission which destroys the consistency of
Democritus' theory. This theory was at least not self-contradictory:
the Epicurean theory is a mixture of dynamism and mechanism which
cannot stand a moment's serious investigation.
The ethics of the Epicurean school is simply the Hedonism of Aristippus
refined under a broader idea of culture and a more enlightened concept
of Socratic Eudemonism. In spite of Socratic influence, the Epicurean
ethics is not, in the strict sense of the word, a system of morality at
all. It contains no principles of morality; it reduces right and wrong
to a matter of individual feeling, substituting for good and
evil the categories pleasant and painful.