“Thought is not essential to existence nor its cause, but it is an instrument for becoming; I become what I see in myself. All that thought suggests to me, I can do; all that thought reveals in me, I can become. This should be man's unshakable faith in himself, because God dwells in him.”

Source: Death in Venice (1912), Ch. 4, as translated by David Luke

Thought as a System (1992)
Context: What I mean by 'thought' is the whole thing — thought, 'felt', the body, the whole society sharing thoughts — it's all one process. It is essential for me not to break that up, because it's all one process; somebody else's thought becomes my thought, and vice versa. Therefore it would be wrong and misleading to break it up into my thought, your thought, my feelings, these feelings, those feelings. I would say that thought makes what is often called in modern language a system. A system means a set of connected things or parts. But the way people commonly use the word nowadays it means something all of whose parts are mutually interdependent — not only for their mutual action, but for their meaning and for their existence. A corporation is organized as a system — it has this department, that department, that department... they don't have any meaning separately; they only can function together. And also the body is a system. Society is a system in some sense. And so on.
Similarly, thought is a system. That system not only includes thought and feelings, but it includes the state of the body; it includes the whole of society — as thought is passing back and forth between people in a process by which thought evolved from ancient times. Thought has been constantly evolving and we can't say when that system began. But with the growth of civilization it has developed a great deal. It was probably very simple thought before civilization, and now it has become very complex and ramified and has much more incoherence than before.
Now, I say that this system has a fault in it — a 'systematic fault'. It is not a fault here, there or here, but it is a fault that is all throughout the system. Can you picture that? It is everywhere and nowhere. You may say "I see a problem here, so I will bring my thoughts to bear on this problem". But "my" thought is part of the system. It has the same fault as the fault I'm trying to look at, or a similar fault.
Thought is constantly creating problems that way and then trying to solve them. But as it tries to solve them it makes it worse because it doesn’t notice that it's creating them, and the more it thinks, the more problems it creates.

As formas superiores do pensamento tem uma tendência fatal a tornar-se na futura lei revelada: e toda a filosofia termina, nos seus velhos dias, por ser religião.
"Israelismo"; "Israelism" p. 50.
Cartas de Inglaterra (1879–82)

Source: Darkness Falls

Source: A Fatal Grace

Ma pensée, c'est moi: voilà pourquoi je ne peux pas m'arrêter. J'existe parce que je pense … et je ne peux pas m'empêcher de penser.
Lundi ("Monday")
Nausea (1938)

Post match press conference after winning Dubai Open 2007. http://sport.guardian.co.uk/tennis/story/0,,2026649,00.html

1979