Heraclitus believed in universal impermanence ("everything is in flux") and that all things (notably opposites) were interrelated. Fragments #20 and #21 show this and also his most well known quote - that of the river. | Heraclitus believed in universal impermanence ("everything is in flux") and that all things (notably opposites) were interrelated. Fragments #20 and #21 show this and also his most well known quote - that of the river. |