Heraclitus of Ephesus was a pre-Socratic Greek philosopher who lived a lonely life earning him the moniker of the Weeping Philosopher. His principal philosophy is embodied in the following statement No man ever steps in the same river twice, in other words man faces an ever-present change in the universe. He believed in the unity of opposites, stating that the path up and down are one and the same. According to Diogenes, Heraclitus worked on a continuous treatise On Nature, which was divided into three discourses, one on the universe, another on politics, and a third on theology. Only fragments of this work remain today many of which are quoted from other authors. Those fragments are presented here in a translation and with critical commentary by G. T. W. Patrick.