How we cite our quotes: (Preface if applicable, Paragraph)
Quote #1
No more is needed to show that the Steppenwolf lived a suicidal existence. But all the same I do not believe that he took his own life when, after paying all he owed but without a word of warning or farewell, he left our town one day and vanished. (Preface 42)
The first hint of Harry's suicidal nature shows up early, in the preface, which is a glimpse of things to come. Later on the treatise will say that he's a suicidal dude, and Harry himself will tell us about his own suicide attempts.
Quote #2
But he has not killed himself, for a glimmer of belief still tells him that he is to drink this frightful suffering in his heart to the dregs, and that it is of this suffering he must die. (Preface 44)
Here suffering is compared to a drink that will kill Harry… kind of like his alcoholism. He has to drink down his suffering just like he drinks down liquor. The narrator of the preface is convinced that Harry hasn't yet done the deed. Do you think he's still alive somewhere, wolfing it up?
Quote #3
What is peculiar to the suicide is that his ego, rightly or wrongly, is felt to be an extremely dangerous, dubious, and doomed germ of nature; that he is always in his own eyes exposed to an extraordinary risk, as though he stood with the slightest foothold on the peak of a crag whence a slight push from without or an instant's weakness from within suffices to precipitate him into the void. (39)
The treatise on the Steppenwolf compares the suicidal person to a germ in this metaphor; then it compares life, for the suicidal person, to standing on the edge of a cliff. Both images convey extreme vulnerability or danger, even if from the outside it doesn't seem like the suicidal person is really doing anything out of the ordinary.
Quote #4
Many of these natures are wholly incapable of ever having recourse to real suicide, because they have a profound consciousness of the sin of doing so. For us they are suicides nonetheless; for they see death and not life as the releaser. (40)
This is an interesting take on suicide, because it isn't about the act of actually killing oneself; it counts the desire to do so in and of itself as suicide. Do you think it's possible to live as a suicide without ever committing suicide?
Quote #5
He gained strength through familiarity with the thought that the emergency exit stood always open, and became curious, too, to taste his sufferings to the dregs. (41)
Comparing suicide to an emergency exit is metaphor that shows us how Harry sees life as a state of urgency and danger. Instead of something to enjoy, life becomes an emergency that must be escaped from.
Quote #6
He appointed his fiftieth birthday as the day on which he might allow himself to take his own life. (42)
Well, happy birthday to you, Harry. This gives Harry a reason to keep on living, paradoxically, because he knows that he can always kill himself later. What a way to celebrate. How would the novel be different if Harry had chosen his 18th birthday or his 30th, for example?
Quote #7
Death was decreed for this Steppenwolf. He must with his own hand make an end of his detested existence-unless, molten in the fire of a renewed self-knowledge, he underwent a change and passed over to a self, new and undisguised. (70)
Finally we get a glimmer of hope. Harry has gone through life up to this point thinking that the only way to get some relief is to kill himself; the book, however, is offering him another option: transforming himself.
Quote #8
Once when despair had again got the better of me I had swallowed a big dose of it—enough to kill six men, and yet it had not killed me. (75)
Either Harry doesn't know how to kill six men or he has superhuman strength. But seriously, he is trying to show us that when he overdosed on his medicine he wasn't just crying for help: he really did want to die.
Quote #9
But I put my resolution in this way: the next time I felt that I must have recourse to the opium, I might allow myself to use big means instead of small, that is, a death of absolute certainty with a bullet or a razor. (76)
Harry compares suicide to opium; it's a strange metaphor, one you don't see every day. Opium dulls the senses and puts you to sleep, so suicide is like a relaxing, soothing medicine for Harry.