Heraclitus of Ephesus was a pre-Socratic
Pre-Socratic philosophy
Pre-Socratic philosophy is Greek philosophy before Socrates . In Classical antiquity, the Presocratic philosophers were called physiologoi...

 Greek philosopher
Greek philosophy
Ancient Greek philosophy arose in the 6th century BCE and continued through the Hellenistic period, at which point Ancient Greece was incorporated in the Roman Empire...

, a native of the Greek city Ephesus
Ephesus was an ancient Greek city, and later a major Roman city, on the west coast of Asia Minor, near present-day Selçuk, Izmir Province, Turkey. It was one of the twelve cities of the Ionian League during the Classical Greek era...

, Ionia
Ionia is an ancient region of central coastal Anatolia in present-day Turkey, the region nearest İzmir, which was historically Smyrna. It consisted of the northernmost territories of the Ionian League of Greek settlements...

, on the coast of Asia Minor
Asia Minor
Asia Minor is a geographical location at the westernmost protrusion of Asia, also called Anatolia, and corresponds to the western two thirds of the Asian part of Turkey...

. He was of distinguished parentage. Little is known about his early life and education, but he regarded himself as self-taught and a pioneer of wisdom. From the lonely life he led, and still more from the riddling nature of his philosophy and his contempt for humankind in general, he was called "The Obscure" and the "Weeping Philosopher".

Heraclitus is famous for his insistence on ever-present change in the universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

, as stated in his famous saying, "No man ever steps in the same river twice" (see panta rhei, below).

Πάντα ῥεῖ καὶ οὐδὲν μένει

Everything flows, nothing stands still.

Nothing endures but change.

From Lives of the Philosophers by Diogenes Laertius

Though wisdom is common, yet the many live as if they had a wisdom of their own.

Fragment 2; Quoted by Sextus Empiricus in Against the Mathematicians

Nature is wont to hide herself.

Fragment 10

Much learning does not teach understanding.

Fragment 16

ἓν τὸ σοφὸν μοῦνον λέγεσθαι οὐκ ἐθέλει καὶ ἐθέλει Ζηνὸς ὄνομα

The wise is one only. It is unwilling and willing to be called by the name of Zeus.

Logos is day and night, winter and summer, war and peace, surfeit and hunger.

Fragment 36