How we cite our quotes: (Volume.Book.Chapter.Line)
Quote #1
[Death] wouldn't be for her a question of a flying leap and thereby of a quick escape. It would be a question of taking full in the face the whole assault of life." (1.3.1.14)
When Susan wonders if Milly is thinking about committing suicide, she quickly dismisses the thought because she knows that Milly is a fighter. Milly isn't going to take the easy way out just because she's sick. She's going to do all the living she can while there's still time.
Quote #2
[Milly] wouldn't have committed suicide; she knew herself unmistakably reserved for some more complicated passage; this was the very vision in which she had, with no little awe, been discovered." (1.3.1.14)
In another meditative moment, Susan convinces herself again that Milly will not commit suicide, despite the odd message of farewell that she's written on the book she's been carrying with her. Ultimately, Milly is destined for something more complicated than suicide, which strikes Susan as too simple and straightforward for her.
Quote #3
"Insist, insist—the more the better. But the day I look as sound and strong as that, you know […] on that day I shall be just sound and strong enough to take leave of you sweetly for ever." (1.4.3.64)
Milly has a bit of a morbid sense of humor, which makes sense when you realize that she's terminally ill. After Susan says that she wants Milly looking good, Milly says she'll never look as good as she will at her funeral, because then she'll be totally immune to injury and sickness. You know, because of the death and all.