.
NEWCOMB, _The Stars: A Study of the Universe_.
OLCOTT, _Field Book of the Stars_.
PRICE, _Essence of Astronomy_.
SERVISS, _Curiosities of the Skies_.
WEBB, _Celestial Objects for Common Telescopes_.
YOUNG, _Text-Book of General Astronomy_.

II

THE STORY OF EVOLUTION

INTRODUCTORY

THE BEGINNING OF THE EARTH--MAKING A HOME FOR LIFE--THE FIRST LIVING
CREATURES

Sec. 1

The Evolution-idea is a master-key that opens many doors. It is a
luminous interpretation of the world, throwing the light of the past
upon the present. Everything is seen to be an antiquity, with a history
behind it--a _natural history_, which enables us to understand in some
measure how it has come to be as it is. We cannot say more than
"understand in some measure," for while the _fact_ of evolution is
certain, we are only beginning to discern the _factors_ that have been
at work.

The evolution-idea is very old, going back to some of the Greek
philosophers, but it is only in modern times that it has become an
essential part of our mental equipment. It is now an everyday
intellectual tool. It was applied to the origin of the solar system and
to the making of the earth before it was applied to plants and animals;
it was extended from these to man himself; it spread to language, to
folk-ways, to institutions. Within recent years the evolution-idea has
been applied to the chemical elements, for it appears that uranium may
change into radium, that radium may produce helium, and that lead is the
final stable result when the changes of uranium are complete. Perhaps
all the elements may be the outcome of an inorganic evolution. Not less
important is the extension of the evolution-idea to the world within as
well as to the world without. For alongside of the evolution of bodies
and brains is the evolution of feelings and emotions, ideas and
imagination.

Organic evolution means that the present is the child of the past and
the parent of the future. It is not a power or a principle; it is a
process--a process of becoming. It means that the present-day animals
and plants and all the subtle inter-relations between them have arisen
in a natural knowable way from a preceding state of affairs on the whole
somewhat simpler, and that again from forms and inter-relations simpler
still, and so on backwards and backwards for millions of years till we
lose all clues in the thick mist that hangs over life's beginnings.

Our solar system