Other Worlds | Page 5

of life, giving rise to a
conviction that one world, even in the material sense, is not enough for
it, but that every planet must belong to its kingdom. We are apt to say
to ourselves: "The earth is one of a number of planets, all similarly
circumstanced; the earth is inhabited, why should not the others also be

inhabited?"
What has been learned of the unity in chemical constitution and
mechanical operation prevailing throughout the solar system, together
with the continually accumulating evidence of the common origin of its
various members, and the identity of the evolutionary processes that
have brought them into being, all tends to strengthen the a priori
hypothesis that life is a phenomenon general to the entire system, and
only absent where its essential and fundamental conditions, for special
and local, and perhaps temporary, reasons, do not exist.
If we look for life in the sun, for instance, while accepting the prevalent
conception of the sun as a center of intense thermal action, we must
abandon all our ideas of the physical organization of life formed upon
what we know of it from experimental evidence. We can not imagine
any form of life that has ever been presented to our senses as existing in
the sun.
But this is not generally true of the planets. Life, in our sense of it, is a
planetary, not a solar, phenomenon, and while we may find reasons for
believing that on some of the planets the conditions are such that
creatures organized like ourselves could not survive, yet we can not
positively say that every form of living organism must necessarily be
excluded from a world whose environment would be unsuited for us
and our contemporaries in terrestrial life.
Although our sole knowledge of animated nature is confined to what
we learn by experience on the earth, yet it is a most entertaining, and by
no means unedifying, occupation, to seek to apply to the exceedingly
diversified conditions prevailing in the other planets, as astronomical
observations reveal them to us, the principles, types, and limitations
that govern the living creatures of our world, and to judge, as best we
can, how far those types and limits may be modified or extended so that
those other planets may reasonably be included among the probable
abodes of life.
In order to form such judgments each planet must be examined by itself,
but first it is desirable to glance at the planetary system as a whole. To

do this we may throw off, in imagination, the dominance of the sun,
and suppose ourselves to be in the midst of open space, far removed
both from the sun and the other stars. In this situation it is only by
chance, or through foreknowledge, that we can distinguish our sun at
all, for it is lost among the stars; and when we discover it we find that it
is only one of the smaller and less conspicuous members of the
sparkling host.
We rapidly approach, and when we have arrived within a distance
comparable with that of its planets, we see that the sun has increased in
apparent magnitude, until now it enormously outshines all the other
stars, and its rays begin to produce the effect of daylight upon the orbs
that they reach. But we are in no danger of mistaking its apparent
superiority to its fellow stars for a real one, because we clearly perceive
that our nearness alone makes it seem so great and overpowering.
And now we observe that this star that we have drawn near to has
attending it a number of minute satellites, faintly shining specks, that
circle about it as if charmed, like night-wandering insects, by its
splendor. It is manifest to us at the first glance that without the sun
these obedient little planets would not exist; it is his attraction that
binds them together in a system, and his rays that make them visible to
one another in the abyss of space. Although they vary in relative size,
yet we observe a striking similarity among them. They are all globular
bodies, they all turn upon their axes, they all travel about the sun in the
same direction, and their paths all lie very nearly in one plane. Some of
them have one or more moons, or satellites, circling about them in
imitation of their own revolution about the sun. Their family
relationship to one another and to the sun is so evident that it colors our
judgment about them as individuals; and when we happen to find, upon
closer approach, that one of them, the earth, is covered with vegetation
and water and filled with thousands of species of animated creatures,
we are disposed to believe, without further examination, that they are
all alike in this