The materialists pull everything down from the sky and out of the invisible world onto the earth as if they wanted to clench rocks and oak trees in their fists. They grasp them, and stubbornly maintain that the only objects that exist are those that are tangible and comprehensible. They believe that the physical existence of an object is existence itself, and look down smugly on other people — those who acknowledge another area of existence separate from the physical. But they are totally unwilling to listen to another point of view.
(Plato, Sophists)(Taken from the epigraph of Jakob von Uexküll's essay The Theory of Meaning.)