MONISM

All things are forms of one substance. Thales said that Water is the material cause of all things. Anaximander said that the Boundless or Infinite is the essence of all things. Anaximenes said that all things arise from a condensation or rarefaction of air. Parmenides said that Being is the one homogeneous and continuous substance. Heraclitus said that Fire is the universal flux or becoming of all things and the first principle of reality. See Epistemological monism