e same. The fact that so many more of these objects
are seen around the galactic belt than in the direction of its poles
shows that, whatever extinction light may suffer in going through the
greatest distances, we see nearly all that comes from stars not more
distant than the Milky Way itself.

Intimately connected with the subject we have discussed is the question
of the age of our system, if age it can be said to have. In considering
this question, the simplest hypothesis to suggest itself is that the
universe has existed forever in some such form as we now see it; that
it is a self-sustaining system, able to go on forever with only such
cycles of transformation as may repeat themselves indefinitely, and
may, therefore, have repeated themselves indefinitely in the past.
Ordinary observation does not make anything known to us which would
seem to invalidate this hypothesis. In looking upon the operations of
the universe, we may liken ourselves to a visitor to the earth from
another sphere who has to draw conclusions about the life of an
individual man from observations extending through a few days. During
that time, he would see no reason why the life of the man should have
either a beginning or an end. He sees a daily round of change, activity
and rest, nutrition and waste; but, at the end of the round, the
individual is seemingly restored to his state of the day before. Why
may not this round have been going on forever, and continue in the
future without end? It would take a profounder course of observation
and a longer time to show that, notwithstanding this seeming
restoration, an imperceptible residual of vital energy, necessary to
the continuance of life, has not been restored, and that the loss of
this residuum day by day must finally result in death.

The case is much the same with the great bodies of the universe.
Although, to superficial observation, it might seem that they could
radiate their light forever, the modern generalizations of physics show
that such cannot be the case. The radiation of light necessarily
involves a corresponding loss of heat and with it the expenditure of
some form of energy. The amount of energy within any body is
necessarily limited. The supply must be exhausted unless the energy of
the light sent out into infinite space is, in some way, restored to the
body which expended it. The possibility of such a restoration
completely transcends our science. How can the little vibration whi