WHAT IT IS AND WHAT IT IS NOT. 57 
turning, is the movement of all life. The changes in 
human history are only typical of the changes that take 
place in all living creatures. In fact, human history is 
only a part of one great life current, the movement of 
which is everywhere governed by the same laws, depends 
on the same forces, and brings about like results, 
The facts and generalizations of change constitute 
the subject matter of evolution; and as the fact of life 
is a fundamental one and in some degree modifies all 
phenomena which it concerns, we have as the central 
axis of the science in question the study of organic evo- 
lution. In fact, while inorganic evolution or orderly 
change in environment also exists, we do not know to 
what degree the laws and forces of organic evolution 
can be reduced to the same terms of expression. The 
theory of the essential and necessary unity of life and 
non-life, of mind and matter, is still a matter of phil- 
osophical speculation only. We can neither prove the 
truth of Monism nor understand it; nor is the contrary 
hypothesis either comprehensible or credible. The 
fundamental unity of organic evolution and inorganic 
evolution is likewise yet to be proved, while the laws 
which govern living matter are certainly in part peculiar 
to life. For this reason the evolution of astronomy, of 
dynamic geology, of geography, as well as the purely 
hypothetical evolution of chemistry, must be separated 
from life evolution. Cosmic evolution and organic evo- 
lution show or seem to show some divergence from each 
other. To regard them as identical is to introduce con- 
fusion and not order into our conception of evolution. 
There are some elements which are not held in com- 
mon, or which at least are not identical when measured 
in human terms. It is not evident that any force in 
the evolution of life is homologous with any which has 
brought about the evolution of stars and planets. This 
