Heraclitus, the pre-Socratic Greek philosopher who lived and wrote 2,500 years ago--around the same time as Confucius, Lao Tzu and the Buddha--is best known as the man who said you cannot put your foot into the same river twice.
Here is how the poet Brooks Haxton, in his fine new translation of Heraclitus, Fragments, the Collected Wisdom of Heraclitus (Viking; 99 pages; $19.95), puts the thought: "The river/where you set/your foot just now/is gone--/those waters/ giving way to this,/now this."
Such fragments are all that is left of Heraclitus' great book, On Nature, which was lost many centuries ago. They come...