No Greek philosopher born before Socrates was more creative and influential
than Heraclitus of Ephesus. Around the beginning of the fifth century
BC, in a prose that made him proverbial for obscurity, he criticized
conventional opinions about the way things are and attacked the authority
of poets and others reputed to be wise. His surviving work consists
of more than 100 epigrammatic sentences, complete in themselves and
often comparable to the proverbs characteristic of ‘wisdom’
literature. Notwithstanding their sporadic presentation and transmission,
Heraclitus’ sentences comprise a philosophy that is clearly focused
upon a determinate set of interlocking ideas.
As interpreted by the later Greek philosophical tradition, Heraclitus
stands primarily for the radical thesis that ‘Everything is in
flux’, like the constant flow of a river. Although it is likely
that he took this thesis to be true, universal flux is too simple a
phrase to identify his philosophy. His focus shifts continually between
two perspectives – the objective and everlasting processes of
nature on the one hand and ordinary human beliefs and values on the
other. He challenges people to come to terms, theoretically and practically,
with the fact that they are living in a world ‘that no god or
human has made’, a world he describes as ‘an ever-living
fire kindling in measures and going out in measures’. His great
truth is that ‘All things are one’, but this unity, far
from excluding difference, opposition and change, actually depends on
them, since the universe is in a continuous state of dynamic equilibrium.
Day and night, up and down, living and dying, heating and cooling –
such pairings of apparent opposites all conform to the everlastingly
rational formula (Logos) that unity consists of opposites;
remove day, and night goes too, just as a river will lose its identity
if it ceases to flow.
Heraclitus requires his audience to try to think away their purely
personal concerns and view the world from this more detached perspective.
By the use of telling examples he highlights the relativity of value
judgments. The implication is that unless people reflect on their experience
and examine themselves, they are condemned to live a dream-like existence
and to remain out of touch with the formula that governs and explains
the nature of things. This formula is connected (symbolically and literally)
with ‘ever-living fire’, whose incessant ‘transformations’
are not only the basic operation of the universe but also essential
to the cycle of life and death. Fire constitutes and symbolizes both
the processes of nature in general and also the light of intelligence.
As the source of life and thought, a ‘fiery’ soul equips
people to look into themselves, to discover the formula of nature and
to live accordingly.
The influence of Heraclitus’ ideas on other philosophers was
extensive. His reputed ‘flux’ doctrine, as disseminated
by his follower Cratylus, helped to shape Plato’s cosmology and
its changeless metaphysical foundations. The Stoics looked back to Heraclitus
as the inspiration for their own conception of divine fire, identifying
this with the logos that he specifies as the world’s explanatory
principle. Later still, the neo-Pyhrronist Aenesidemus invoked Heraclitus
as a partial precursor of skepticism.