of mankind is to be found in the existing state of our earth, the
conditions which make it a fit abode for our kind, and replete with
lessons which he may study with his own eyes without having to travel
the difficult paths of the higher sciences.

Although physiography necessarily takes some account of the things
which have been, even in the remote past, and this for the reason that
everything in this day of the world depends on the events of earlier
days, the accent of its teaching is on the immediate, visible, as we
may say, living world, which is a part of the life of all its
inhabitants.




CHAPTER III.

THE STELLAR REALM.


Even before men came to take any careful account of the Nature
immediately about them they began to conjecture and in a way to
inquire concerning the stars and the other heavenly bodies. It is
difficult for us to imagine how hard it was for students to gain any
adequate idea of what those lights in the sky really are. At first men
imagined the celestial bodies to be, as they seemed, small objects not
very far away. Among the Greeks the view grew up that the heavens were
formed of crystal spheres in which the lights were placed, much as
lanterns may be hung upon a ceiling. These spheres were conceived to
be one above the other; the planets were on the lower of them, and the