ore, if such an Aether can explain the phenomena associated with
our own system, it ought also to explain, and that to the fullest
extent, all phenomena incidental to and associated with the innumerable
systems that flood the universe at large.

[Footnote 44: _Outlines of Astronomy._]

CHAPTER XIV

UNITY OF UNIVERSE

ART. 123. _The Universe._--In the preceding chapters we have endeavoured
to deal with some of the principal phenomena that help to give a
mechanical conception to the entire Universe.

It now remains for us to show, in this last chapter, how, underlying all
the physical structure of the Universe, there is one fundamental and
primordial medium, in which all the forms of matter and motion find
their ultimate unity.

The Universe literally means one ultimate whole, though that whole may
be compounded of many parts, the very essence of the term embodying the
idea of a complete unity which runs throughout its whole physical
structure.

Apart from some such hypothesis as will be suggested in this chapter,
that ultimate unity is incapable of a physical or mechanical conception.
In Art. 29 we learned that the Universe was composed of two classes of
things, matter and motion, while in Art. 30 we learned that the sum
total of matter according to the law of the conservation of matter ever
remains the same; while further, in Art. 53, according to the law of the
conservation of energy, the sum total of energy ever remains the same.
We have also learned that the two are indissolubly united, so that
wherever we found matter, whether that matter was in its atomic,
molecular, planetary or stellar form, there, as its necessary complement
and counterpart, was the ever-present and unceasing motion, in one or
other of its many forms. Thus, throughout the entire Universe, we find
the same two essentials ever working in unison and harmony.

Nowhere in the realm of infinite space is there such a phenomenon as
rest or absolute death. The ideal that seems to be the key of the
Universe, is that continuity of motion which science teaches us is so
inseparably connected with all matter. Grouped, however, here and there
throughout the Universe are modifications of this aetherial matter,
termed molecules, satellites, planets, suns, or stars, which
modifications are, however, not so real and abiding as the
electro-magnetic Aether from which they receive their physica