more certainly for its own work sure and sifted material. But all attempts
which can not {112} submit to this renunciation, give only an apparent
right to that view which Albert Lange, in his "History of Materialism,"
defends, when he banishes speculative philosophy to the realm of
imagination.

But in rejecting philosophy in the question of the causes of the
development and organization of the organic kingdoms, we did not reach the
end of the philosophic problems with which we are confronted. This whole
question is itself only a segment of the problems before which we stand,
and leads of necessity to other questions.

Already within the series of development of the organic world, so far as it
is investigated by natural science, we have found and named a point (at the
end of Sec. 1, Chap. II, Book I), where the competency of pure natural science
comes to an end, and the question arises whether another source of
knowledge--_i.e._, even philosophy--can not take up the investigation where
natural science completes its task. This point was the _origin of
self-consciousness_ and of _free moral self-determination_; consequently,
the origin of that which makes man _man_. Going still farther back on the
temporal and ideal scale of organic beings, we arrive at another point,
which natural science no longer can explain, and that is the _origin of
sensation_ and of _consciousness_. With the appearance of sensation and
consciousness, the _animal world_ came into existence. Moreover, the whole
scientific question as to the origin and development of species, so far as
we have hitherto treated it, started from initial points where the organic
and life already existed; it, therefore, leads of necessity to the further
question as to _the origin of the organic and of life itself_. D. F.
Strauss, {113} in his "Postscript as Preface," thus clearly and simply
characterizes these still unfilled blanks in the evolution theory: "There
are, as is well known, three points in the rising development of nature, to
which the appearance of incomprehensibility especially adheres (to speak
more categorically: which have not been explained thus far by anybody). The
three questions are: How has the living sprung from that which is without
life? the sentient (and conscious) being from that which is without
sensation? that which possesses reason (self-consciousness and free will)
from that which is without reason?--questions equally embarrassing to
thought