safe to guess that they possess a knowledge of the surface of the earth
far exceeding in minuteness and accuracy the knowledge that we possess
of the features of any heavenly body except the moon. They must long ago
have been able to form definite conclusions concerning the meteorology
and the probable habitability of our planet.

It certainly tends to increase our interest in Venus when, granting
that she is inhabited, we reflect upon the penetrating scrutiny of which
the earth may be the object whenever Venus--as happens once every 584
days--passes between us and the sun. The spectacle of our great planet,
glowing in its fullest splendor in the midnight sky, pied and streaked
with water, land, cloud, and snow, is one that might well excite among
the astronomers of another world, so fortunately placed to observe it,
an interest even greater than that which the recurrence of total solar
eclipses occasions upon the earth. For the inhabitants of Venus the
study of the earth must be the most absorbing branch of observational
astronomy, and the subject, we may imagine, of numberless volumes of
learned memoirs, far exceeding in the definiteness of their conclusions
the books that we have written about the physical characteristics of
other members of the solar system. And, if we are to look for attempts
on the part of the inhabitants of other worlds to communicate with us by
signals across the ether, it would certainly seem that Venus is the
most likely source of such efforts, for from no other planet can those
features of the earth that give evidence of its habitability be so
clearly discerned. Of one thing it would seem we may be certain: if
Venus has intellectual inhabitants they possess far more convincing
evidence of our existence than we are likely ever to have of theirs.

In referring to the view of the earth from Mercury it was remarked that
the moon is probably visible to the naked eye. From Venus the moon is