Heraclitus was a Greek philosopher who lived around 500 BCE in the city of Ephesus. Unlike philosophers who searched for stability or permanence, Heraclitus believed that the universe is defined by continuous motion.
Heraclitus — difficult, solitary, known to his contemporaries as the Obscure — wrote that everything is in a state of perpetual flux ... I have been thinking about Heraclitus a great deal lately ... Heraclitus again ... This is Heraclitus’s river again.