To say that Wittgenstein laid the groundwork for logical positivism is pushing it slightly; what Wittgenstein considered to be beyond language and (thus) beyond reason was taken by the positivists to be meaningless. Wittgenstein himself states in his Tractatus "And unless I am mistaken in this regard, then this book has worth secondly in displaying how little is achieved with the solution to these problems", referring to all philosophical problems. The translation (from Finnish this time) is mine, but should be fairly accurate. Wittgenstein alludes to the importance of what cannot be said by showing that logical pictures or thoughts are tautological.

Wittgenstein and Hitler's time in the same school in Linz is documented in a book called 'The Jew of Linz'