The subjects of change in the vibrations are the electric or magnetic polarisations of the medium in which they take place. In order to explain the propagation of light in space between the stars, which is free from all trace of ponderable matter, the electromagnetic theory of light also must assume a medium, which fills the world-space even where no ponderable matter is to be found. It must so far make the same assumption as the undulatory theory (of light); but while the latter has to ascribe the properties of a solidly-elastic body to the ether, no assumption at all need be made by the electromagnetic theory as to the mode of its inner consistence. It is enough, that the ether is capable of being magnetised, and electrified in the fashion of an insulator, that is, in such a way that in its smallest parts a certain electric distribution, a so-called dielectric polarisation, as Faraday named it, is possible.

What It Means

This is a placeholder explanation generated by the low-overhead model. It interprets "The subjects of change in the vibrations are the electric or magnetic polarisations of the medium in which they take place. In order to explain the propagation of light in space between the stars, which is free from all trace of ponderable matter, the electromagnetic theory of light also must assume a medium, which fills the world-space even where no ponderable matter is to be found. It must so far make the same assumption as the undulatory theory (of light); but while the latter has to ascribe the properties of a solidly-elastic body to the ether, no assumption at all need be made by the electromagnetic theory as to the mode of its inner consistence. It is enough, that the ether is capable of being magnetised, and electrified in the fashion of an insulator, that is, in such a way that in its smallest parts a certain electric distribution, a so-called dielectric polarisation, as Faraday named it, is possible." in the context of "Hermann von Helmholtz, Vorlesungen über die Elektromagnetische Theorie des Lichts (1897) § 13 p. 43, as quoted by Shadworth Hodgson, Positive science, in The Metaphysics of Experience Book II (1898) p. 189 footnote." to mean that wisdom is timeless.