Modern science does not recognize the four elements of fire, air, water, and earth. The solid, liquid, and gaseous forms of matter are not elements. The Greek concept of nature was based on the recognition of the four elements. Somewhat as a fifth, ether was added. Aristotle said of ether: “It is that which is different from earth, water, air, and fire; it is eternal and eternally revolves in a circle.” The elements have their origin in the center, the ethers in the periphery. The former are central, the latter peripheral; the former are point-like, individual; the latter universal, comprehensive. Mathematically speaking, one could say they relate to each other like plus and minus, positive and negative.