282 TRANSLATION OF "DE LUCE ET LUMINE." on the other. Sound likewise is heard from within a solid body, though more faint; as we see in sounds within the bloodstone, or in bodies struck under water; whereas light in a solid and untransparent body that is stopped on all sides, is not seen at all. Lastly, all sound is generated in motion and a manifest elision of bodies; but light not so. For the oppositions to light, unless you take privations to mean oppositions, there are none that occur to me; but what is most credible is that sluggishness of bodies in their parts is the chief enemy to light. For there is scarce anything luminous which is not either in its own nature very movable, or excited by heat or motion or the vital spirit. Other instances. I mean always, not only that other instances are to be sought for (for these few are only adduced by way of example), but likewise that new topics of inquiry should be added, as the nature of things leads the way. |