gnition of things to seek
the _ground_, and _reason_, and _law_ of things. It is the effort of
reason to solve the great problem of "Being and Becoming," of appearance
and reality, of the changeful and the permanent. Beneath the endless
diversity of the universe, of existence and action, there must be a
principle of unity; below all fleeting appearances there must be a
permanent substance; beyond this everlasting flow and change, this
beginning and ending of finite existence, there must be an _eternal
being_, the source and cause of all we see and know, _What is that
principle of unity, that permanent substance_, or principle, or being?

This fundamental question has assumed three separate forms or aspects in
the history of philosophy. These forms have been determined by the
objective phenomena which most immediately arrested and engaged the
attention of men. If external nature has been the chief object of
attention, then the problem of philosophy has been, _What is the
arche--_the beginning; what are the first principles_--the elements from
which, the ideas or laws according to which, the efficient cause or
energy by which, and the reason or end for which the universe exists?_
During this period reflective thought was a PHILOSOPHY OF NATURE. If the
phenomena of mind--the opinions, beliefs, judgments of men--are the
chief object of attention, then the problem of philosophy has been,
_What are the fundamental Ideas which are unchangeable and permanent
amid all the diversities of human opinions, connecting appearance with
reality, and constituting a ground of certain knowledge or absolute
truth?_ Reflective thought is now a PHILOSOPHY OF IDEAS. Then, lastly,
if the practical activities of life and the means of well-being be the
grand object of attention, then the problem of philosophy has been,
_What is the ultimate standard by which, amid all the diversities of
human conduct, we may determine what is right and good in individual,
social, and political life?_ And now reflective thought is a PHILOSOPHY
OF LIFE. These are the grand problems with which philosophy has grappled
ever since the dawn of reflection. They all appear in Greek philosophy,
and have a marked chronology. As systems they succeed each other, just
as rigorously as the phenomena of Greek civilization.

The Greek schools of philosophy have been classified from various points
of view. In view of their geographical relations, they have been divided
into the _