The truth stares me in the face: this man is going to die soon. (16.95)
When he sees a respected doctor walk into a restaurant, Antoine is overcome by certainty that the man will soon die. He can see it is the guy's face, and Antoine is very good at sizing people up with one look.
Or else he was dead, up there above my head. Found dead in bed one foggy morning—sub-heading: in the café, customers went on eating without suspecting. (19.50)
Antoine thinks about the way that world just keeps going when someone dies. After all, other people have their own business to deal with.
Suppose he's dead. (19.43)
When the owner of the Café Mably doesn't come down at his usual time, an old woman wonder out loud if he might be dead up in his bed. It's a morbid thought, but the casual way she brings it up shows us that death is a possibility to lingers over every second of our lives.
Naked to the waist, his body a little green, like that of a dead man, the bachelor was lying on an unmade bed. The disorder of sheets and blankets attested to a long death agony. (21.6)
When he checks out a painting called "The Bachelor's Death," Antoine realizes that the world is condemning him for not getting married and settling down. Basically, the paint's message is: get married and have children or else no one will care when you die.
I had not gone far enough the other day: experience was much more than a defence against death; it was a right; the right of old men. (21.22)
In a moment of flickering hope, Antoine looks at some portraits of respectable old men and realizes how brave they would have been to make meaning of their lives even in old age. In this case, he believes that experience isn't just a state of not-being-dead. It's actually something you can make meaningful if you live with freedom, dignity, and purpose.
Suddenly they existed, then suddenly they existed no longer: existence is without memory; of the vanished it retains nothing—not even a memory. (25.12)
For Antoine, death totally erases an entire person's life. You either exist or you don't, and when you die, it doesn't matter whether you've had kids or written a bunch of books. There's no such thing as living on after you're dead. Once you die, it's as if you never existed to begin with.
My past is dead. The Marquis de Rollebon is dead, Anny came back only to take all hope away. (31.2).
When Antoine finally gives up on his history project, he realizes that all it ever was was a distraction from the absurdity of his own existence. He used to think that getting Anny back would help him, too. But now he realizes that there's no getting away from the true of existence once it's been revealed to you. Now he feels like every part of him is dead.
"Maybe he is going to kill himself." No: this gentle, baited soul could never dream of death. (33.6)
After the Self-Taught Man gets banned from the Bouville library, Antoine wonders if the guy will kill himself. But he quickly loses the thought, since he knows that the STM is too gentle to do something so drastic. Let's hope he's right.
A year from now I'd find myself as empty as I am today, without even a memory, and a coward facing death. (33.36)
Antoine considers spending his entire fortune for the sake of getting a thrill out of life again. But he knows that if he did this, he would leave himself with nothing. Not even his memories would be important, since he believes that things only exist in the here and now. All he would have left would be death.
But behind the existence which falls from one present to the other, without a past, without a future, behind these souls which decompose from day to day, peel off and slip towards death, the melody stays the same, young and firm. (33.50)
Death is the inevitable outcome of life, says Antoine, and it's tough to argue with him. But where Antoine gets into dicey territory is when he says that death totally erases our existence altogether. For Antoine, there is no heaven and hell, and on top of that, our deaths totally erase everything we've ever done with our lives, making it so that we might as well never have existed to begin with.