photographic plate at the rate of more than 800 billion waves a
second, they take several hours to register the faintest point of
light on the plate.

When we reflect that the universe has grown with the growth of
our telescopes and the application of photography we wonder
whether we may as yet see only a fraction of the real universe,
as small in comparison with the whole as the Babylonian system
was in comparison with ours. We must be content to wonder. Some
affirm that the universe is infinite; others that it is limited.
We have no firm ground in science for either assertion. Those who
claim that the system is limited point out that, as the stars
decrease in brightness, they increase so enormously in number
that the greater faintness is more than compensated, and
therefore, if there were an infinite series of magnitudes, the
midnight sky would be a blaze of light. But this theoretical
reasoning does not allow for dense regions of space that may
obstruct the light, or vast regions of vacancy between vast
systems of stars. Even apart from the evidence that dark nebulae
or other special light-absorbing regions do exist, the question
is under discussion in science at the present moment whether
light is not absorbed in the passage through ordinary space.
There is reason to think that it is. Let us leave precarious
speculations about finiteness and infinity to philosophers, and
take the universe as we know it.

Picture, then, on the more moderate estimate, these 500,000,000
suns scattered over tens of thousands of billions of miles.
Whether they form one stupendous system, and what its structure
may be, is too obscure a subject to be discussed here. Imagine