ince I
first became aware that I had accepted, even from my youth,
many false opinions for true, and that consequently what I
afterward based on such principles was highly doubtful; and
from that time I was convinced of the necessity of undertaking
once in my life to rid myself of all the opinions I had
adopted, and of commencing anew the work of building from the
foundation, if I desired to establish a firm and abiding
superstructure in the sciences."[155:7]

Leibniz's mind was more predominantly logical even than Descartes's. He
sought in philosophy a supreme intellectual synthesis, a science of the
universe.

"Although," he says retrospectively, "I am one of those who
have worked much at mathematics, I have none the less
meditated upon philosophy from my youth up; for it always
seemed to me that there was a possibility of establishing
something solid in philosophy by clear demonstrations. . . .
I perceived, after much meditation, that it is impossible to
find the _principles of a real unity_ in matter alone, or in
that which is only passive, since it is nothing but a
collection or aggregation of parts _ad infinitum_."[155:8]

[Sidenote: The Historical Differentiation of the Philosophical Problem.]

Sect. 59. Though these types are peculiarly representative, they are by
no means exhaustive. There are as many possibilities of emphasis as
there are incentives to philosophical reflection. It is not possible to
exhaust the aspects of experience which may serve as bases from which
such thought may issue, and to which, after its synthetic insight, it
may return. But it is evident that such divisions of philosophy
represent in their order, and in the sharpness with which they are
sundered, the intellectual autobiography of the individual philosopher.
There is but one method by which that which is peculiar either to the
individual, or to the special position which he adopts, may be
eliminated. Though it is impossible to tabulate the empty programme of
philosophy, we may name certain special problems that have appeared _in
its history_. Since this history comprehends the activities of many
individuals, a general validity attaches to it. There has been,
moreover, a certain periodicity in the emergence of these problems, so
that it may fairly be claimed for them that they indicate inevitable
phases in the development of human reflection upo