sea in which the atoms of
the material bodies are as islands, and it occupies the whole of what we
call empty space. It is so sensitive that a disturbance in any part of
it causes a "tremour which is felt on the surface of countless worlds."
Our old experiences of matter give us no account of any substance like
this; yet the undulatory theory of light obliges us to admit such a
substance, and that theory is as well established as the theory of
gravitation. Obviously we have here an enlargement of our experience
of matter. The analysis of the phenomena of light and radiant heat has
brought us into mental relations with matter in a different state from
any in which we previously knew it. For the supposition that the ether
may be something essentially different from matter is contradicted by
all the terms we have used in describing it. Strange and contradictory
as its properties may seem, are they any more strange than the
properties of a gas would seem if we were for the first time to discover
a gas after heretofore knowing nothing but solids and liquids? I think
not; and the conclusion implied by our authors seems to me eminently
probable, that in the so-called ether we have simply a state of matter
more primitive than what we know as the gaseous state. Indeed, the
conceptions of matter now current, and inherited from barbarous ages,
are likely enough to be crude in the extreme. It is not strange that
the study of such subtle agencies as heat and light should oblige us
to modify them; and it will not be strange if the study of electricity
should entail still further revision of our ideas.

We are now brought to one of the profoundest speculations of modern
times, the vortex-atom theory of Helmholtz and Thomson, in which the
evolution of ordinary matter from ether is plainly indicated. The
reader first needs to know what vortex-motion is; and this has been
so beautifully explained by Professor Clifford, that I quote his
description entire: "Imagine a ring of india-rubber, made by joining
together the ends of a cylindrical piece (like a lead-pencil before
it is cut), to be put upon a round stick which it will just fit with a
little stretching. Let the stick be now pulled through the ring while
the latter is kept in its place by being pulled the other way on the
outside. The india-rubber has then what is called vortex-motion. Before
the ends were joined together, while it was straight, it might have been
made to turn aroun