is that at this rate he would put down all natural
philosophy, as far as it concerns itself in searching into the
nature of such things. In such noble and sublime studies as these,
'tis a glory to arrive at probability, and the search itself
rewards the pains. But there are many degrees of probable, some
nearer to the truth than others, in the determining of which lies
the chief exercise of our judgment. And besides the nobleness and
pleasure of the studies, may we not be so bold as to say that they
are no small help to the advancement of wisdom and
morality?--HUYGHENS, _Conjectures concerning the Planetary Worlds_.

The interest with which astronomy is studied by many who care little or
nothing for other sciences is due chiefly to the thoughts which the
celestial bodies suggest respecting life in other worlds than ours.
There is no feeling more deeply seated in the human heart--not the
belief in higher than human powers, not the hope of immortality, not
even the fear of death--than the faith in realms of life where other
conditions are experienced than those we are acquainted with here. It is
not vulgar curiosity or idle fancy that suggests the possibilities of
life in other worlds. It has been the conviction of the profoundest
thinkers, of men of highest imagination. The mystery of the star-depths
has had its charm for the mathematician as well as for the poet; for
the exact observer as for the most fruitful theoriser; nay, for the man
of business as for him whose life is passed in communing with nature. If
we analyse the interest with which the generality of men inquire into
astronomical matters apparently not connected with the question of life
in other worlds, we find in every case that it has been out of this
question alone or chiefly that that interest has sprung. The great
discoveries made during the last few years respecting the sun for
example, might seem remote from the subject of life in other worlds. It
is true that Sir William Herschel thought the sun might be the abode of
living creatures; and Sir John Herschel even suggested the possibility
that the vast streaks of light called the solar willow-leaves, objects
varying from two hundred to a thousand miles in length, might be living
creatures whose intense lustre was the measure of their intense
vitality. But modern discoveries had rendered all such theories
untenable. The sun is presented to us as a mighty fu