which we classify as forces or energies. These points of disturbance
cluster together in systems (atoms) of from 1000 to 250,000 members,
and the atoms are pressed together until they come in the end to form
massive worlds. It remains only to reduce gravitation itself, which
brings the atoms together, to a strain or stress in ether, and we have
a superb unity. That has not yet been done, but every theory of
gravitation assumes that it is a stress in the ether corresponding to
the formation of the minute disturbances which we call electrons.

But, it may be urged, he who speaks of foundations speaks of a beginning
of a structure; he who speaks of evolution must have a starting-point.
Was there a time when the ether was a smooth, continuous fluid, without
electrons or atoms, and did they gradually appear in it, like crystals
in the mother-lye? In science we know nothing of a beginning. The
question of the eternity or non-eternity of matter (or ether) is as
futile as the question about its infinity or finiteness. We shall see in
the next chapter that science can trace the processes of nature back
for hundreds, if not thousands, of millions of years, and has ground to
think that the universe then presented much the same aspect as it does
now, and will in thousands of millions of years to come. But if these
periods were quadrillions, instead of millions, of years, they would
still have no relation to the idea of eternity. All that we can say is
that we find nothing in nature that points to a beginning or an end. [*]

* A theory has been advanced by some physicists that there
is evidence of a beginning. WITHIN OUR EXPERIENCE energy is
being converted into heat more abundantly than heat is being
converted into other energy. This would hold out a prospect
of a paralysed universe, and that stage would have been
reached long ago if the system had not had a definite
beginning. But what knowledge have we of conversions of
energy in remote regions of space, in the depths of stars or
nebulae, or in the sub-material world of which we have just
caught a glimpse? Roundly, none. The speculation is
worthless.

One point only need be mentioned in conclusion. Do we anywhere perceive
the evolution of the material elements out of electrons, just as we
perceive the devolution, or disintegration, of atoms into electrons?
There is good ground for thinking that we do. The subject will be