Perhaps it was a passing moment of madness after all. There is no trace of it left anymore. (1.10)
When Antoine first experiences his feelings of "Nausea," he thinks that he might be falling into mental illness. But the feeling quickly passes, and he makes the mistake of thinking that it will never come back. But guess what? It will.
I'm going to bed. I'm cured. I'll give up writing my daily impressions, like a little girl in her nice new notebook. (1.14)
Antoine starts writing a diary in order to cope with the disorder that mental illness has brought into his daily life. But the moment his boredom and despair leave him, he thinks he's cured and that the worst is over. He even thinks he's been silly for writing a diary, comparing himself to a "little girl" writing in a notebook. Little does Antoine know that his struggles with "Nausea" are going to define him for the rest of this book.
I know all that, but I know there is something else. Almost nothing. But I can't explain what I see. To anyone. There: I am quietly slipping into the water's depths, towards fear. (3.16)
When his feelings of fear and disgust come back, Antoine has trouble putting his experience into words. The reason for this is because his fear exists on a level beneath language, on the level of pure existence, which for him is "almost nothing." As he slips further into this experience, his main feeling is fear. Again, we're forced to ask ourselves whether he is really coming to new intellectual truths… or if he is just losing his mind.
He visited each one of them and, with an incomparable power, mimed the scene which was to take place. Thus he caused to be born or developed in them a madness for murder. (6.9)
While researching the Marquis de Rollebon, Antoine wonders whether it's truly possible for one person to be so persuasive that he can turn other people crazy. In this instance, it seems like the Marquis was such a convincing speaker and actor that he got a bunch of men to crave murder so badly that they went insane and killed the ruler of Russia.
I am cold, I take a step, I am cold, a step, I turn left, he turns left, he thinks he turns left, mad, am I mad? (22.39)
Antoine really starts to question his sanity when he writes the word "I" and no longer knows who it refers to. He says "I," but since his mind is changing from one second to the next, his true self is always slipping away from the word "I," which is supposed to refer to him. If this sounds confusing, that's because it is. Just ask Antoine.
Why not? It would be a change in any case. I put my left hand on the pad and stab the knife into the palm. The movement was too nervous; the blade slipped, the wound is superficial. (22.36)
Sitting at a café table, Antoine picks up a knife and stabs himself in the hand. He's so bored and lonely that he just wants to feel something.Anything.
A crazy loon: he relaxes, he feels protected against himself: nothing will happen to him today. I am reassured too. A crazy old loon: so that was it, so that was all. (16.81)
When the strange man named M. Achille enters the café, Antoine almost feels relieved to know that there is someone around who is crazier than him. The problem with M. Achille, though, is that he doesn't feel responsible for what he does with his life because he's been labeled as "crazy." For Sartre, individuals are always responsible for their actions, and psychological explanations can't undo this fact.
It's strange that everything makes so little difference to me: it frightens me. (24.280)
Antoine is downright scared by how little he cares about the people and things around him. It doesn't make any difference to him if any of them are dead or alive. In short, he wishes that he felt more connected to things, since this is apparently how a person is "supposed" to feel.
I feel as though I could do anything. For example, stab this cheese knife into the Self-Taught Man's eye. (24.282)
When he realizes that the world is an absurd place and human life has no higher meaning, Antoine feels like he has total freedom to do whatever he wants. There's no God to tell him what's moral or not, so he totally has the freedom to pick up a knife and stab his friend in the eye. Of course, he'd have to deal with the consequences, like going to jail. But he can still do it if he's willing to take responsibility.
He goes to the mirror, opens his mouth: and his tongue is an enormous, live centipede, rubbing its legs together and scraping his palate. (31.8)
How's this for crazy? Toward the end of the novel, Antoine speculates on just how nutty the world would have to get before people took notice and actually started seeing the world in new ways. For example, does a person have to wake up with a bug for a tongue before he actually stops taking everything for granted? It sounds kind of crazy, but it makes a good point about how numbly people go through their everyday lives.