9.     Poincaré explains that the unity of nature expresses itself in the similar relation among the "Milky Way," "dust in fluid," and "gaseous molecules": "if the different parts of the universe were not organs of the same body, they would not re-act one upon the other...We need not, therefore, ask if Nature is one, but how she is one" (Poincaré, 1902/1952, p. 145).