FragmentsBy: Heraclitus Fragments of wisdom from the ancient world In the sixth century b. c. twenty five hundred years before Einstein Heraclitus of Ephesus declared that energy is the essence of matter, that everything becomes energy in flux, in relativity. His great book, On Nature, the world's first coherent philosophical treatise and touchstone for Plato, Aristotle, and Marcus Aurelius, has long been lost to history but its surviving fragments have for