2901. The speech of animals is a vocal or vowel-speech.
5. Function of the Optic Sense.
2902. As the primary motion of the world is manifested to the animal through the ear; so does the primitive cause of the motion, that of every activity and every phenomenon, i. e. light, appear unto the nerve-sense.
2903. The light-sense is similarly formed or modelled according to the light of nature, and kindles also the light within itself, just as the light originated in the æther; viz. through primary antagonism taking place in its own substance.
2904. Light is the binary division of the æther-mass, not an antagonism between it and some other matter; in like manner sight is a binary division of the nerve-mass in itself, without antagonism to other organs.
2905. Sight is the tension of the æther directly continued into the animal æther, just as taste was a chemical action continued into the animal chemism, and smell an electrical process continued into the animal electrism.
2906. In sight the nervous mass is completely self-antagonized, is a phenomenon unto itself; the eye is the brain placed opposite to the brain.
2907. Sight is thus a tension between optic and central brain; as illumination is tension between planetary and solar æther.
2908. Illumination and vision are of one kind, only occurring in two different sorts of worlds. The planet sees by means of the illumination, the animal illuminates or gives out light by means of seeing. Sight is a light-sense.
2909. Now, the illumination is a fixation of æther, a coloration, and thus a descent of the æther into what is terrestrial. In seeing we perceive the æther, as to how it becomes world; in hearing we perceived the world, as to how it became æther.