4.1122 Darwin's theory has no more to do with philosophy than any other
hypothesis in natural science.


4.113 Philosophy sets limits to the much disputed sphere of natural
science.


4.114 It must set limits to what can be thought; and, in doing so, to what
cannot be thought. It must set limits to what cannot be thought by working
outwards through what can be thought.


4.115 It will signify what cannot be said, by presenting clearly what can
be said.


4.116 Everything that can be thought at all can be thought clearly.
Everything that can be put into words can be put clearly. 4.12 Propositions
can represent the whole of reality, but they cannot represent what they
must have in common with reality in order to be able to represent it--
logical form. In order to be able to represent logical form, we should have
to be able to station ourselves with propositions somewhere outside logic,
that is to say outside the world.


4.121 Propositions cannot represent logical form: it is mirrored in them.
What finds its reflection in language, language cannot represent. What
expresses itself in language, we cannot express by means of language.