been calculated that on a clear night the total starlight from the
entire celestial sphere amounts to one-sixtieth of the light of the
full moon; but of this less than one-twenty-fifth is due to stars
separately distinguished by the eye. If there were no obscuring medium
in space, it is probable that the amount of starlight would be
noticeably and perhaps enormously increased.

But while it seems certain that some of the obscure spots in the Milky
Way are due to the presence of ``dark nebulæ,'' or concealing veils of
one kind or another, it is equally certain that there are many which
are true apertures, however they may have been formed, and by whatever
forces they may be maintained. These, then, are veritable windows of
the Galaxy, and when looking out of them one is face to face with the
great mystery of infinite space. There the known universe visibly
ends, but manifestly space itself does not end there. It is not within
the power of thought to conceive an end to space, for the instant we
think of a terminal point or line the mind leaps forward to the
beyond. There must be space outside as well as inside. Eternity of
time and infinity of space are ideas that the intellect cannot fully
grasp, but neither can it grasp the idea of a limitation to either
space or time. The metaphysical conceptions of hypergeometry, or
fourth-dimensional space, do not aid us.

Having, then, discovered that the universe is a thing contained in
something indefinitely greater than itself; having looked out of its
windows and found only the gloom of starless night outside -- what
conclusions are we to draw concerning the beyond? It seems as empty as
a vacuum, but is it really so? If it be, then our universe is a single
atom astray in the infinite; it is the only island in an ocean without
shores; it is the one oasis in an illimitable desert. Then the Milky