called a _new_ science, and some explanation of the fact that it has
only recently advanced to form a distinct department in our educational
system. The reason is not difficult to find. Biology is a new science,
not because the objects it studies are new, but because it has adopted a
new relation to those objects and is studying them from a new
standpoint. Animals and plants have been studied long enough, but not as
we now study them. Perhaps the new attitude adopted toward living nature
may be tersely expressed by saying that in the past it has been studied
as _at rest_, while to-day it is studied as _in motion_. The older
zoologists and botanists confined themselves largely to the study of
animals and plants simply as so many museum specimens to be arranged on
shelves with appropriate names. The modern biologist is studying these
same objects as intensely active beings and as parts of an ever-changing
history. To the student of natural history fifty years ago, animals and
plants were objects to be _classified_; to the biologist of to-day, they
are objects to be _explained_.

To understand this new attitude, a brief review of the history of the
fundamental features of philosophical thought will be necessary. When,
long ago, man began to think upon the phenomena of nature, he was able
to understand almost nothing. In his inability to comprehend the
activities going on around him he came to regard the forces of nature as
manifestations of some supernatural beings. This was eminently natural.
He had a direct consciousness of his own power to act, and it was
natural for him to assume that the activities going on around him were
caused by similar powers on the part of some being like himself, only
superior to him. Thus he came to fill the unseen universe with gods
controlling the forces of nature. The wind was the breath of one god,
and the lightning a bolt thrown from the hands of another.