‘Concerning what you write about thoughts of suicide,’ Engelmann added, ‘my thoughts are as follows’:

Behind such thoughts, just as in others, there can probably lie something of a noble motive. But that this motive shows itself in this way, that it takes the form of a contemplation of suicide, is certainly wrong. Suicide is certainly a mistake. So long as a person lives, he is never completely lost. What drives a man to suicide is, however, the fear that he is completely lost. This fear is, in view of what has already been said, ungrounded. In this fear a person does the worst thing he can do, he deprives himself of the time in which it would be possible for him to escape being lost.

‘You undoubtedly know all this better than I,’ wrote Engelmann, excusing himself for appearing to have something to teach Wittgenstein, ‘but one sometimes forgets what one knows.’

Ray Monk, Ludwig Wittgenstein: The Duty of Genius, London, 1990, pp. 186-187