pends on so many
conditions, hereditary and otherwise, that we cannot regard the
inferior development of humanity in the tropics as due solely to
temperature. Physically considered, no men attain a better development
than many tribes who inhabit the warmer regions of the globe. The
inferiority of the inhabitants of these regions in intellectual power
is more likely the result of race heredity than of temperature.

We all know that this earth on which we dwell is only one of countless
millions of globes scattered through the wilds of infinite space. So
far as we know, most of these globes are wholly unlike the earth, being
at a temperature so high that, like our sun, they shine by their own
light. In such worlds we may regard it as quite certain that no
organized life could exist. But evidence is continually increasing that
dark and opaque worlds like ours exist and revolve around their suns,
as the earth on which we dwell revolves around its central luminary.
Although the number of such globes yet discovered is not great, the
circumstances under which they are found lead us to believe that the
actual number may be as great as that of the visible stars which stud
the sky. If so, the probabilities are that millions of them are
essentially similar to our own globe. Have we any reason to believe
that life exists on these other worlds?

The reader will not expect me to answer this question positively. It
must be admitted that, scientifically, we have no light upon the
question, and therefore no positive grounds for reaching a conclusion.
We can only reason by analogy and by what we know of the origin and
conditions of life around us, and assume that the same agencies which
are at play here would be found at play under similar conditions in
other parts of the universe.

If we ask what the opinion of men has been, we know historically that
our race has, in all periods of its history, peopled other regions with
beings even higher in the scale of development than we are ourselves.
The gods and demons of an earlier age all wielded powers greater than
those granted to man--powers which they could use to determine human
destiny. But, up to the time that Copernicus showed that the planets
were other worlds, the location of these imaginary beings was rather
indefinite. It was therefore quite natural that when the moon and
planets were found to be dark globes of a size comparable with that of
the earth itself, they were made the ha