The Summary of Physics Restored

193Nature’s fire should be numbered among spiritual things, for in itself it cannot be perceived by any sense. It reveals itself in bodies through heat and other effects and accidents, as is evident in animals, into which the imperceptible fire of Nature pours perceptible heat. When that fire silently withdraws and life goes with it, the elemental body or corpse remains whole and uninjured, although the mixed body has been dissolved. In plants, however, because this fire is weaker, it eludes sense and does not allow itself to be felt through heat.