Heráclito

Heráclito of Ephesus, often called Heraclitus, was a pre-Socratic Greek philosopher active in the city of Ephesus (in Ionia, on the western coast of Asia Minor) during the late 6th and early 5th centuries BCE. Details of his life are fragmentary, and his writings survive only in quotations and fragments preserved by later authors.

Core to Heraclitus’ thought is the view that reality is in constant flux. He is famous for the claim that everything changes and that one cannot step into the same river twice, a succinct expression of the broader idea that becoming replaces static being. He also claimed that there is a single underlying order or principle, which he called the logos, a rational structure that governs the cosmos even if most people fail to recognize it. Opposites are interdependent and reconciled within this dynamic unity; for example, conflict and harmony are intertwined in the process of change.

Many fragments imply fire as a primordial element or arche that embodies transformation and the process of becoming, though interpretations vary on whether fire is a literal or symbolic representation of change. He also suggested that sensory perception yields opinion rather than true knowledge, and that genuine understanding comes through grasping the logos.

His work, titled On Nature (Peri Physeos), exists only in fragments quoted by later writers. Heraclitus influenced later philosophers, including Plato and Aristotle, and his ideas were later adopted by the Stoics. Modern scholarship typically treats his writings as cryptic and highly allusive, with ongoing debate about exact doctrine and emphasis.