  “The surface is where most of the action is. The surface is where light is reflected or absorbed, not the interior of the substance. The surface is what touches the animal, not the interior. The surface is where chemical reactions mostly take place. The surface is where vaporization or diffusion of substances into the medium occurs. And the surface is where vibrations of the substance are transmitted into the medium.” [J. J. Gibson, The Ecological Approach to Visual Perception (1979: 23)]