Because I am so cut off I naturally have an extraordinarily strong desire for a friend ...

Wittgenstein in a letter, 1908

His disposition is that of an artist, intuitive and moody. He says every morning he begins his work with hope, and every evening he sends in despair - he has just the sort of rage when he can't understand things that I have.

Russell on Wittgenstein, in a letter to Morell, 1912

... perhaps the most perfect example I have ever known of genius as traditionally conceived, passionate, profound, intense, and dominating.

Russell on Wittgenstein in his Autobiography

We expect the next big step in philosophy to be taken by your brother.

Russell, speaking to Wittgenstein's sister, Hermine, 1912

He would, according to Russell, 'pace up and down my room like a wild beast for three hours in agitated silence'. Once, Russell asked: 'Are you thinking about logic or your sins?' 'Both', Wittgenstein replied, and continued his pacing.

Ray Monk, from whose biography all these quotations are taken.

... the year spent in Skjolden was possibly the most productive of his life. Years later he used to look back on it as the one time that he had had some thoughts that were enirely his own, when he had even 'brought to life new movements in thinking'. 'Then my mind was on fire!', he used to say.

Monk again, writing of Wittgenstein's time in Norway in 1913.

My day passes between logic, whistling, going for walks, and being depressed. I wish to God that I were more intelligent and everything would finally become clear to me - or else that I needn't live much longer.

... deep inside me there's a perpetual seething, like the bottom of a geyser, and I keep hoping that things will come to an eruption once and for all, so that I can turn into a different person.

Perhaps you regard this thinking about myself as a waste of time - but how can I be a logician before I'm a human being? Far the most important thing is to settle accounts with myself!

Wittgenstein to Russell, Xmas 1913

Worked the whole day. Stormed the problem in vain! But I would pour my blood before this fortress rather than march off empty-handed. The greatest difficulty lies in making secure fortresses already conquered. And as long as the whole city has not fallen one cannot feel completely secure in one of its fortifications.

letter, October 1914

My thoughts are tired. I am not seeing things freshly, but rather in a pedestrian, lifeless way. It is as if a flame had gone out and I must wait until it starts to burn again by itself.

letter, Jan 1915

Yesterday I was shot at. I was scared! I was afraid of death. I now have such a desire to live. And it is difficult to give up life when one enjoys it. This is precisely what 'sin' is, the unreasoning life, a false view of life. From time to time I become an animal. Then I can think of nothing but eating, drinking and sleeping. Terrible! And then I suffer like an animal too, without the possibility of internal salvation. I am then at the mercy of my appetites and aversions. Then an authentic life is unthinkable.

Diary entry 1916

I have continually thought of taking my own life, and the idea still haunts me sometimes. I have sunk to the lowest point. May you never be in that position! Shall I ever be able to raise myself up again?

Wittgenstein to Engelmann, May 1920

The best for me, perhaps, would be if I could lie down one evening and not wake up again.

Wittgenstein to Russell, July 1920

I had a task, did not do it, and now the failure is wrecking my life. I ought to have done something positive with my life, to have become a star in the sky. Instead of which I remained stuck on earth, and now I am gradually fading out. My life has really become meaningless and so it consists only in futile episodes. The people around me do not notice this and would not understand; but I know that I have a fundamental deficiency. Be glad of it, if you don't understand what I am writing here.

Wittgenstein to Engelmann, 1921

But it is hard to have to be a teacher in this country where the people are so completely and utterly hopeless. In this place I do not have a soul with whom I can exchange a single reasonable word. God knows how I will be able to stand it for much longer!

Wittgenstein to Russell, 1921

We haven't met since 11 years. I don't know if you have changed during that time, but I certainly have tremendously. I am sorry to say I am no better than I was, but I am different. And therefore if we shall meet you may find that the man who has come to see you isn't really the one you meant to invite. There is no doubt that, even if we can make ourselves understood to one another, a chat or two will not be sufficient for the purpose, and that the result of our meeting will be disappointment and disgust on your side and disgust and despair on mine.

Wittgenstein to Keynes, 1924

I no longer feel any hope for the future of my life. It is as though I had before me nothing more than a long stretch of living death. I cannot imagine any future for me other than a ghastly one. Friendless and joyless.

[...] I suffer greatly from the fear of the complete isolation which threatens me now., I cannot see how I can bear this life. I see it as a life in which every day I have to fear the evening that brings me only dull sadness.

My unhappiness is so complex that it is difficult to describe. But probably the main thing is still loneliness.

I have suffered much, but I am apparently incapable of learning from my life. I suffer still just as I did many years ago. I have not become any stronger or wiser.

I feel that my mental health is hanging on a thin thread.

from Wittgenstein's Diaries, April-September 1942