These visible films or membranous exurse of objects, which the old philosophers talked about, have no real existence, separable from their illuminated source, and perish instantly when it is withdrawn. The man beholdeth himself in the glass and goeth his way, and straightway both the mirror and the mirrored forget what manner of man he was. But remove the cause,-the body itself-and the effect is removed. Under the action of light, then, a body makes its superficial aspect potentially present at a distance, becoming appreciable as a shadow or as a picture. Yet the images will not be the same for the one taken a mile off will be very small, at half a mile as large again, at a hundred feet fifty times as large, and so on, as long as the mirror can contain the image.
They must be packed like the leaves of a closed book for suppose a mirror to give an image of an object a mile off, it will give one at every point less than a mile, though this were subdivided into a million parts. These evanescent films may be seen in one of their aspects in any clear, calm sheet of water, in a mirror, in the eye of an animal by one who looks at it in front, but better still by the consciousness behind the eye in the ordinary act of vision. Cortex is, indeed, one of the names applied to them by Lucretius. They are perpetually shed from the surfaces of solids, as bark is shed by trees. Forms, effigies, membranes, or films, are the nearest representatives of the terms applied to these effluences.
Those who are curious on the matter will find the poet's description at the beginning of his fourth book. Epicurus borrowed the idea from him, and incorporated it into the famous system, of which Lueretius has given us the most popular version. DEMOCRITIUS of Abdera, commonly known as the Laughing Philosopher, probably because he did not consider the study of truth inconsistent with a cheerful countenance, believed and taught that all bodies were continually throwing off certain images like themselves, which subtile emanations, striking on our bodily organs, gave rise to our sensations.
0 kommentar(er)
