These are separated from the Earlier Ionian philosophers not merely in
point of time but also in respect to doctrine. The difference consists
chiefly in the tendency which the Later Ionians manifest to depart
from the monistic dynamism of the early physicists and adopt a
dualistic mechanical concept of the universe. Heraclitus, who is, in
ultimate analysis, a dynamist, marks the beginning of the change which,
after the more or less hesitating utterances of Empedocles, appears
successively in the mechanism of the Atomists and in the openly
pronounced dualism of Anaxagoras. Heraclitus is, therefore, the
connecting link between earlier and later Ionian philosophy.
Life. Heraclitus, surnamed the Obscure (ho skoteinos) on
account of the mist of oracular expressions in which (purposely,
according to some writers) he veiled his teachings, was born at Ephesus
about the year 530 B.C. He composed a work peri phuseôs,
consisting of three parts,  the first of which was peri tou
pantos the second, (logos) politikos and the third,
(logos) theologikos. Of the fragments which have come down to
us, very few can be assigned to the second of these parts, and fewer
still to the third. The existing fragments offer considerable
difficulty in the matter of arrangement and interpretation, a
difficulty which is increased by the fact that many of our secondary
authorities are untrustworthy. The doctrines of Heraclitus resemble the
fundamental tenets of the Stoics, and here as elsewhere the stoic
historians are inclined to exaggerate such resemblances. On this
account, even for modern scholars, Heraclitus is still the Obscure.
 Cf. Diog. Laer., IX, 7. References are to the work peri ton
biôn, dogmatikôn kai apophthegmatôn tôn en
philosophia eudokimêsantôn (ed. Cobet, Paris, 1850), which
is attributed to Diogenes Laertius.
Sources. Besides the fragments above mentioned, we have as
sources of information the writings of Plato and Aristotle, who give a
tolerably complete account of the teachings of Heraclitus.
Doctrine of Universal Change. Heraclitus places himself in
direct opposition to the Eleatic teaching and to the data of common,
unreflecting consciousness. The mass of men -- and here he includes not
merely Pythagoras and Xenophanes but also Homer and Hesiod, associating
them with the common herd -- see nothing but sense-forms; they fail to
comprehend the all-discerning reason.  We should follow reason
alone. "Much learning does not teach the mind." 
 Frag. 18. The numbers used are those used by Burnet, following
Bywater, Her. Eph. Reliquiae (Oxford, 1877).
 Frag. 16.
Now, the first lesson which reason teaches us is that there is
nothing permanent in the world around us. The senses, when they
attribute to things a permanence which things do not possess, are
deceived and thus give rise to the greatest of all errors, the belief
in immobility. The truth is that all things change, panta
chôrei. Everything is involved in the stream of change: from
life comes death, from death comes life; old age succeeds youth; sleep
changes into wakefulness and wakefulness into sleep. In a word, nothing
is, all is Becoming.
Both Plato  and Aristotle  set down the doctrine of the
universality of change as being the most characteristic of the
teachings of Heraclitus. Plato, moreover, expressly mentions the
Heraclitean comparison of the stream in which wave succeeds wave. But
it is remarkable that the expression, "All things are flowing," which
so conveniently sums up the doctrine of universal change, cannot be
proved to be a quotation from the work of Heraclitus.
 Theaet., 160 D, and Cratyl.. 401 D.
 Met., IV, 5, 1010a, 13, and De An., I, 2, 405 a, 25.
Doctrine of Fire. Another source of error is this: that the
poets and sages knew no more than the common herd does about the
divine, all-controlling fire. By fire, however, Heraclitus
meant invisible warm matter rather than the fire which is the result
of combustion. It is endowed with life, or at least with the power of
Becoming -- "All things are exchanged for fire and fire for all
things, just as wares are exchanged for gold and gold for wares."  It
is, therefore, what Aristotle would call the material as well as the
efficient cause of all things, -- and here Heraclitus shows himself the
lineal descendant of the Earlier Ionians. Moreover, since all things
proceed from fire according to fixed law, fire is styled Zeus, Deity,
 Frag. 22.
This account would, however, be incomplete without some mention of the
force which is postulated by Heraclitus as coeternal with fire. "Strife
is the father of all, and king of all, and some he made gods, and some,
men."  Opposed to strife, which gave rise to things by separation, is
harmony, which guides them back to the fire whence they came. These
expressions, however, while they speak the language of dualism, are not
to be understood as more than mere figures of speech, for fire, and
fire alone, is the cause of all change.
 Frag. 44.
Origin of the World. The world was produced by the
transformations of the primitive fire. There is a cycle of changes by
which fire through a process of condensation, or rather of
quenching (sbennusthai), becomes water and earth. This is
the downward way. And there is a cycle of changes by which through a
process of rarefaction, or kindling (haptesthai), earth
goes back to water and water to fire. This is the upward way. Now, the
one is precisely the inverse of the other: hodos anô katô
 Frag. 69.
Thus did the world originate and thus does it constantly tend to return
whence it came. Concord is ever undoing the work of strife, and one day
strife will be overcome; but then the Deity, as it were in sport, will
construct a new world in which strife and concord will once more be at
 Frag. 79; cf. note apud Fairbanks, op. cit.,
Doctrine of Opposites. From this continual change comes the
doctrine of opposites. There is a constant swaying (like the
bending and relaxing of a bow), in which all things pass
successively through their opposites: heat becomes cold, dryness
becomes moisture, etc. To produce the new, like must be coupled with
unlike; high and low, the accordant with the discordant, are joined,
that out of one may come all, and out of all, one. On account of this
doctrine Heraclitus is censured by Aristotle  and his commentators
for denying the principle of contradiction. Hegelians, on the other
hand, credit Heraclitus with being the first to recognize the unity of
opposites, the identity of Being and not-Being.  The truth is that
Heraclitus deserves neither the blame of the Aristotelians nor the
praise of the Hegelians. He does not affirm opposite predicates of the
same subject at the same time and sub eodem respectu. Moreover,
his is a physical, not a logical, theory, and to maintain the unity of
opposites in the concrete is not the same as to hold the identity of
Being and not-Being in the abstract.
 Frag. 45.
 Met., IV, 3, 1005 b.
 Cf. Hegel, Gesch. des Phil., I, 305; Werke,
XIII, 305; trans. by Haldane, I, 283.
Anthropological Doctrines. Man, body and soul, originated from
fire. The body is of itself rigid and lifeless, an object of aversion
when the soul has departed from it. The soul, on the other hand, is
divine fire preserved in its purest form. "The driest soul is wisest
and best."  If the soul fire is quenched by moisture, reason is lost.
Like everything else in nature, the soul is constantly changing. It is
fed by fire, or warm matter, which enters as breath or is received
through the senses. Not. withstanding this view, Heraclitus in several
of the fragments speaks of future reward and of the fate of the soul in
 Frag. 74.
 Cf. Zeller, Pre-Socratic Phil., II, 85.
Heraclitus distrusted sense-knowledge: "Eyes and ears," he said,
"are bad witnesses to men, if they have souls that
understand not their language."  Rational knowledge is alone
trustworthy. Heraclitus, however, did not, nor did any of the
pre-Socratic philosophers, attempt to determine the conditions of
rational knowledge. That task was first undertaken by Socrates.
 Frag. 4.
Ethical Doctrines. Heraclitus did not undertake a systematic
treatment of ethical questions. Nevertheless, he prepared the way for
Stoicism by teaching that Immutable Reason is the law of the moral as
well as of the physical world. "Men should defend law as they would a
fortress."  We must subject ourselves to universal order if we wish
to be truly happy: "the character of a man is his guardian
divinity."  This is the doctrine of contentment, or
equanimity (euarestêsis), in which, according to
the Heracliteans, Heraclitus placed the supreme happiness of man.
 Frag. 100.
 Frag. 121.
Historical Position. Even in ancient times Heraclitus was
regarded as one of the greatest physicists. He was deservedly
styled ho phusikos for, while others among the philosophers of
nature excelled him in particular points of doctrine, he had the
peculiar merit of having established a universal point of view for the
study of nature as a whole. He was the first to call attention to the
transitoriness of the individual and the permanence of the law which
governs individual changes, thus formulating the problem to which Plato
and Aristotle afterwards addressed themselves as to the paramount
question of metaphysics. The naïve conception of the universe as
evolved, according to the Earlier Ionians, from one substance, by a
process which may be witnessed in a water tank, now gives place to the
notion of a world ruled in its origin and in all its processes by an
all-pervading Logos. Moreover, though Heraclitus formulated no system
of epistemology, his distrust of the senses and his advocacy of
rational knowledge show that philosophy had begun to emerge from the
state of primitive innocence. It was this germ of
criticism which was developed into full-grown Scepticism by Cratylus,
while along another line of development it led to the critical
philosophy of the Sophists and to the Socratic doctrine of the concept.
Heraclitus and the Eleatics were, so to speak, at opposite poles of
thought. In the doctrines of Empedocles and the Atomists we can
perceive the direct influence of the Eleatic school.
Life. Empedocles, who is the most typical representative of the
Later Ionian school, holds a middle course between the monism of
Parmenides and the extreme panmetabolism of Heraclitus. He was born at
Agrigentum, in Sicily, about the year 490 B.C. According to Aristotle,
he lived sixty years. The tradition which represents Empedocles as
traveling through Sicily and southern Italy and claiming divine honors
wherever he went is only too abundantly proved by fragments of his
sacred poems. The story, however, that he committed suicide by leaping
into the crater of Etna is a malicious invention; it is always
mentioned with a hostile purpose, and usually in order to counteract
some tale told by his adherents and admirers.
Sources. Empedocles, who was a poet as well as a philosopher,
composed two poetico-philosophical treatises, the one metaphysical
(peri phuseôs), and the other theological
(katharmoi). Of the five thousand verses which these poems
contained, only about four hundred and fifty have come down to us. On
account of the language and imagery which Empedocles employs, he is
styled by Aristotle the first rhetorician. 
 Cf. Zeller, Pre-Socratic Phil., II, 119, n.
Metaphysics. Empedocles, like Parmenides, begins with a denial
of Becoming. Becoming, in the strict sense of qualitative change of an
original substance, is unthinkable. Yet, with Heraclitus, he holds that
particular things arise, change, decay, and perish. He reconciles the
two positions by teaching that generation is but the commingling, while
decay is the separation of primitive substances which themselves remain
 Verses 98 ff.
The primitive substances are four: fire, air, earth, and
water; these afterwards came to be known as the Four Elements.
Empedocles calls them roots (tessara tôn pantôn
hrizômata). The word elements (stoicheia) was first
used by Plato. The mythological names which Empedocles applied to these
radical principles of Being have no particular philosophical value;
they may be regarded as the accidents of poetical composition. The
elements are underived, imperishable, homogeneous. Definite substances
are produced when the elements are combined in certain proportions.
Now, the moving cause, the force, which produces these combinations is
not inherent in the elements themselves; it is distinct from them. Here
we have the first word of mechanism in Greek philosophy. It is true,
Empedocles speaks of this force as love and hatred, 
but the phraseology merely proves that the idea of force is not yet
clear to the Greek mind: Empedocles does not define the difference
between force and matter on the one hand, and between force and person
on the other. Moreover, to deny that Empedocles was a dualist, to
explain that by love and hatred he meant merely a poetical description
of the conditions of mixture and separation, and not the true causes of
these processes, would imply that Aristotle and all our other
authorities misunderstood the whole doctrine of Empedocles.
 Verse 80.
Cosmological Doctrines. The four elements were originally
combined in a sphere (eudaimonestatos theos) where love
reigned supreme.  Gradually hatred began to exert its centrifugal
influence; love, however, united the elements once more to form those
things which were made. And so the world is given over to love and
hatred, and to the endless pulsation of periodic changes.
 Arist., Met., I, 4, 985 a.
Biological Doctrines. Empedocles seems to have devoted special
attention to the study of living organisms. Plants first sprang from
the earth before it was illumined by the sun; and
then came animals, which were evolved out of all sorts of monstrous
combinations of organisms by a kind of survival of the fit; for those
only survived which were capable of subsisting.  In this theory
Empedocles expressly includes man.
 Verses 245-270.
The cause of growth in animals and plants is fire striving
upwards impelled by the desire to reach its like, the fire which is in
the sky. Blood is the seat of the soul, because in blood the elements
are best united.  It is by reason of the movement of the blood that
inspiration and respiration take place through the pores which are
closely packed together all over the body. 
 Theophr., De Sensu, 10; cf. Diels, op. cit.,
 Verses 288 ff.
Psychological Doctrines. Sense-knowledge is explained by the
doctrine of emanations and pores.  Like is known by like, that is,
things are known to us by means of like elements in us, "earth by
earth, water by water," etc.  In the case of sight, there is an
emanation from the eye itself, which goes out to meet the emanation
from the object.  Thought and intelligence are ascribed to all things,
no distinction being made between corporeal and incorporeal. Thought,
therefore, like all other vital activities, depends on the mixture of
the four elements.  Yet Empedocles seems to contrast the
untrustworthiness of sense-knowledge with knowledge acquired by
reflection, or rather with knowledge acquired by all the powers of the
mind.  He did not conceive the soul as composed of elements; he did not
consider it as an entity apart from the body; he merely explained its
activities by the constitution of the body. In his sacred poem,
however, he adopted the doctrine of transmigration, borrowing it from
Pythagorean and Orphic tradition, without making it part of his
scientific theories. "Once ere now I was a youth, and a maiden, a
shrub, a bird, and a fish that swims in silence in the sea." 
 Verse 281.
 Verse 333.
 Verses 316 ff.
 Zeller, Pre-Socratic Phil., II, 167.
 Verse 19.
 Verse 383. For various readings of this line, cf. Ritter
and Preller, op. cit., p. 150.
Concerning the Gods. Empedocles sometimes speaks as if he held
the common polytheistic belief. Sometimes, on the contrary, as in
verses 345 to 350, he describes the Deity almost in the words of
Xenophanes: "He is sacred and unutterable mind, flashing through the
whole world with rapid thoughts." Still, Empedocles apparently found no
means of introducing this concept of the Deity into his account of the
origin of the universe.
Historical Position. While Empedocles holds a recognized place
among the Greek poets, and while Plato and Aristotle appear to rank him
highly as a philosopher, yet scholars are not agreed as to his precise
place in the history of pre-Socratic speculation. Ritter classes him
with the Eleatics, others count him among the disciples of Pythagoras,
while others again place him among the Ionians on account of the
similarity of his doctrines to those of Heraclitus and the early
Physicists. The truth, as Zeller says, seems to be that there is in the
philosophy of Empedocles an admixture of all these influences, --
Eleatic (denial of Becoming, untrustworthiness of the senses),
Pythagorean (doctrine of transmigration), and Ionic (the four elements
and love and hatred, -- these being an adaptation of Heraclitean
ideas). It would be a mistake, however, to underestimate the
originality of Empedocles as a philosopher. It was he who introduced
the notion of element, fixed the number of elements, and prepared the
way for the atomistic mechanism of Leucippus. The defects, however, of
his metaphysical system are many, chief among them being, as
Aristotle remarked, the omission of the idea of an intelligent Ruler
under whose action natural processes would be regular instead of
 De Gen. et Corr., II, 6, 333 b.
Life. Anaxagoras was born at Clazomenae about 500 B.C.
Aristotle  says that he was "prior to Empedocles in point of age, but
subsequent to him in respect to doctrine." From his native city he went
to Athens, where he was for many years the friend of Pericles, and where he counted
among his disciples the dramatist Euripides. When, shortly before the
outbreak of the Peloponnesian War, Pericles was attacked, Anaxagoras
was tried on the charge of impiety, but escaped from prison and,
returning to his native Ionia, settled in Lampsacus, where he died
about the year 430 B.C.
 Met., I, 3, 984 a, II.
Sources. Diogenes Laertius says that Anaxagoras wrote a work
which, like most of the ancient philosophical treatises, was entitled
peri physeôs. Of this work Plato speaks in the
Apology; in the sixth century of our era Simplicius could still
procure a copy, and it is to him that we owe such fragments as have
come down to us. These fragments were edited by Schaubach in 1827, and
by Schorn in 1829. They are printed by Mullach. 
 Fragmenta, Vol. I, pp. 249 ff.
Starting Point. Like Empedocles, Anaxagoras starts with the
denial of Becoming, and, like Empedocles also, he is chiefly concerned
to explain, in accordance with this denial, the plurality and change
which exist. He differs, however, from Empedocles, both in his doctrine
of primitive substances and in his doctrine of the cosmic force which
formed the universe.
Doctrine of Primitive Substances. Anaxagoras maintained that all
things were formed out of an agglomerate of substances in which bodies
of determinate quality -- gold, flesh, bones, etc. -- were commingled
in infinitely small particles to form the germs of all things.  This
agglomerate was called by Aristotle ta homoiomerê it was
called by Anaxagoras seeds (stêrmata) and things
(chrêmata). So complete was the mixture, and so small were
the particles of individual substances composing it, that at the
beginning no substance could be perceived in its individual nature and
qualities, and accordingly the mixture as a whole might be said to be
qualitatively indeterminate, though definite qualities were really
present in it. Yet, minute as were the primitive particles, they were
divisible. Thus the agglomerate on the one hand reminds us of the
apeiron of Anaximander, and
on the other hand bears a certain analogy to the atomistic concept of
 Frag. 1.
Mind (Nous) is the moving power which formed the world
from the primitive mass of "seeds." Anaxagoras is the first to
introduce into philosophy the idea of the supersensible, for which
reason Aristotle describes him  as standing out "like a sober man
from the crowd of random talkers who preceded him." Mind is
distinguished from other things because (1) it is simple --
everything else is mingled of all things; mind alone is unmixed. It is
"the thinnest of all things and the purest." (2) It is
self-ruled (autokratês). (3) It has all
knowledge about everything. (4) It has supreme power over all
 Met., I, 3, 984 b, 17.
 Frag. 6.
However, as Plato and Aristotle point out, Anaxagoras did not work out
his theory of mind in the details of the cosmic processes. He did not
formulate the idea of design, nor did he apply the principle of design
to particular cases. Mind was for him merely a world-forming force.
There is, moreover, a certain vagueness attaching to the idea of
Nous. Without entering into the details of the question of
interpretation,  we may conclude that although Anaxagoras certainly
meant by the Nous something incorporeal, he could not avoid
speaking of it in terms which, taken literally, imply corporeal nature;
for it is the fate of new ideas to suffer from imperfect expression
until philosophical terminology has adjusted itself to the new
conditions which they create.
 Cf. Zeller, op. cit., II, 342 ff.; Archiv f.
Gesch. der Phil., Ed. VIII (1895), pp. 151, 461-465; also
Philosophical Review, Vol. IV (September, 1895), p. 565, and
Mind, N.S., Vol. V (1896), p. 210.
Cosmology. Mind, therefore, first imparted to matter a circular
motion  separating Air (from which came water, earth, and stone, and
whatever is cold, dark, and dense) and Ether (from which came whatever
is warm, light, and rare). Throughout this account of the processes of
things Anaxagoras considers
the material cause only, thereby deserving Aristotle's reproach, that
he used the Nous merely as a Deus ex machina.
 Frags. 7 and 8.
Psychology. Like is not known by like, but rather by unlike,
and in this Anaxagoras is directly opposed to Empedocles. The senses
are "weak but not deceitful"; the faculty of true knowledge is
Nous, the principle of understanding, which is also  an
intrinsic psychic principle -- the soul. Plutarch's statement  that
Anaxagoras represented the soul as perishing after its separation from
the body is, to say the least, unreliable.
 Theophr., De Sensu, frag. 27; cf. Diels,
Doxographi, p. 507.
From the foregoing it is evident that Anaxagoras was not a Sceptic. The
reason which he alleges for the untrustworthiness of the senses is that
they see only part of what is in the object.  The intellect, which is
unmixed, is capable of seeing the everything which is in everything.
 Frag. 6.
Historical Position. The special importance of the philosophy of
Anaxagoras is due to his doctrine of immaterial mind. This doctrine
implies the most pronounced dualism; it contains in germ the
teleological concept which was evolved by Socrates and perfected by
Plato and Aristotle. It was only natural that these philosophers, who
approached metaphysical problems with minds already accustomed to the
idea of the immaterial, should blame Anaxagoras for not having made
better use of that idea. But we must not underrate the service which
Anaxagoras rendered to Greek philosophy by his doctrine of immaterial
Diogenes of Apollonia and Archelaus of Athens, who are
sometimes included among the Later Ionian philosophers, exhibit a
tendency towards a return to the hylozoism of the first