y that this all-pervading plenum merits the name
of matter. But that it is a something, and a vastly important something
at that, all are agreed. Without it, they allege, we should know nothing
of light, of radiant heat, of electricity or magnetism; without it there
would probably be no such thing as gravitation; nay, they even hint that
without this strange something, ether, there would be no such thing as
matter in the universe. If these contentions of the modern physicist are
justified, then this intangible ether is incomparably the most important
as well as the "largest and most uniform substance or body" in the
universe. Its discovery may well be looked upon as one of the most
important feats of the nineteenth century.

For a discovery of that century it surely is, in the sense that all
the known evidences of its existence were gathered in that epoch.
True dreamers of all ages have, for metaphysical reasons, imagined the
existence of intangible fluids in space--they had, indeed, peopled
space several times over with different kinds of ethers, as Maxwell
remarks--but such vague dreamings no more constituted the discovery of
the modern ether than the dream of some pre-Columbian visionary that
land might lie beyond the unknown waters constituted the discovery
of America. In justice it must be admitted that Huyghens, the
seventeenth-century originator of the undulatory theory of light, caught
a glimpse of the true ether; but his contemporaries and some eight
generations of his successors were utterly deaf to his claims; so
he bears practically the same relation to the nineteenth-century
discoverers of ether that the Norseman bears to Columbus.

The true Columbus of the ether was Thomas Young. His discovery was
consummated in the early days of the nineteenth century, when he brought
forward the first, conclusive proofs of the undulatory theory of light.
To say that light consists of undulations is to postulate something that
undulates; and this something could not be air, for air exists only in
infinitesimal quantity, if at all, in the interstellar spaces, through
which light freely penetrates. But if not air, what then? Why, clearly,
something more intangible than air; something supersensible, evading all
direct efforts to detect it, yet existing everywhere in seemingly
vacant space, and also interpenetrating the substance of all transparent
liquids and solids, if not, indeed, of all tangible substances. This
intangib