Later, they were joined in these musical sessions by a local coal-miner called Heinrich Postl, a member of the village choir. Postl, who became a good friend and a kind of protégé of Wittgenstein’s, was later employed as a porter and caretaker by the Wittgenstein family. Wittgenstein gave him copies of some of his favourite books – Tolstoy’s Gospel in Brief and Hebel’s Schatzkästlein – and sought to impress upon him his own moral teaching. Thus, when Postl once remarked that he wished to improve the world, Wittgenstein replied: ‘Just improve yourself; that is the only thing you can do to better the world.’
Source: Ray Monk, Ludwig Wittgenstein: The Duty of Genius (London: Vintage, 1991), p. 213.