Wittgenstein has become a complete mystic.

I had felt in [the Tractatus] a flavour of mysticism, but was astonished when I found [Wittgenstein] has become a complete mystic. He reads people like Kierkegaard and Angelus Silesius, and he seriously contemplates becoming a monk. It all started from William James's Varieties of Religious Experience, and grew (not unnaturally) during the winter he spent alone in Norway before the war, when he was nearly mad. Then during the war a curious thing happened. He went on duty to the town of Tarnov in Galicia, and happened to come upon a bookshop, which, however, seemed to contain nothing but picture postcards. However, he went inside and found that it contained just one book: Tolstoy on the Gospels. He bought it merely because there was no other. He read it and re-read it, and thenceforth had it always with him, under fire and at all times. But on the whole he likes Tolstoy less than Dostoewski (especially Karamazov). He has penetrated deep into mystical ways of thought and feeling, but I think (though he wouldn't agree) that what he likes best in mysticism is its power to make him stop thinking.

Carta de Bertrand Russell a Ottoline Morrell, Inverno de 1919.