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THE NATURAL SCIENCES. 451
earth's crust it is by no means necessary to assume that
great and stupendous catastrophes have occurred, but that
the forces of nature, slowly but continuously at work
around us, are a sufficient explanation. He referred to the
action of rivers and seas, of springs and glaciers, and compared
the changes of the inorganic world to the minutehand
of a clock, " the advance of which one can see and
hear, while the fluctuations of living creation are hardly to
be seen and resemble the movement of the hour-hand." *
The dogma of fixity of species was gradually abandoned
by most investigators of nature. Men saw that species
do change within certain morphological limits and they
were constrained to adopt the opinion that species had
developed in a similar way into their present forms.
To CHARLES DARWIN belongs the never-to-be-forgotten
merit of having raised the hypothesis into a scientific fact.
Supported by a rich collection of observations he undertook
to fathom the causes which lie at the root of an
explanation of the origin of species, and he came to the
•conclusion that the struggle for existence and natural
selection lead to a survival of the better and fitter
•organisms, followed by a suppression of the conquered and
the gradual perfecting of the conquerors. This theory,
corrected and enlarged at certain points by WALLACE,
NAEGELI and others, formed the foundation of a new
method of contemplating the world of organic nature.
When, soon after, the attempt was made to construct a
history of creation in accordance with the ordinary course
of nature, and when the place of man in relation to the
other inhabitants of the earth was introduced into the
sphere of discussion, the new doctrine excited the vehement
animosity of those who discerned in it an assault upon
religion and upon the dignity of the human race. The
incompleteness of the facts, especially in palaeontology,
and the meagre knowledge which we possess of many processes
in physiology and the history of development did
* O. SCHMIDT: Descendenzlehre und Darwinismus, Leipzig 1873, S. 117.