Heraclitus
Heraclitus was a Greek philosopher from Ephesus on the coast of Asia Minor, active around 500 BCE. He wrote a single book, lost since antiquity; about 130 sayings survive as quotations in later writers. They describe a world-order that is everlasting fire, a single account (logos) that governs all things, and opposites that are held together by their tension. Ancient readers called him "the Obscure" for his riddling style.