On Nature
On Nature (; "Peri Physeos") is a philosophical treatise written by Heraclitus. According to Diogenes Laërtius, it was divided into three discourses; one on the universe, another on politics (and ethics), and one on theology. Theophrastus says (in Diogenes) "... some parts of his work are half-finished, while other parts make a strange medley." The original title is unknown.