How we cite our quotes: (Act.Scene.Line)
Quote #7
Thou in our miseries Fortune have a part,
Yet in our noble suff'rings she hath none.
Contempt of pain—that we call our own. (5.3.54-56)
Here's Antonio, speaking to Delio right before he sneaks into the Cardinals' palace to try and talk things out with him. His attitude is distinctly different from Bosola's. Yeah, Fortune may have something to do with the fact that we suffer in the first place, but the dignity with which we handle that suffering is all down to our exceptional human-ness.
Think about this quote alongside the Duchess's experiences during her imprisonment and execution: many would argue that her comportment during those scenes exemplifies exactly what Antonio's talking about here. She suffers, but does so nobly, and her "contempt of pain" (and, ultimately, the world at large) is frequently cited as a iconic example of human dignity.
Quote #8
We are merely the stars' tennis balls, struck and banded
Which way please them. (5.4.54-55)
There's been plenty of talk about Fate having it in for our characters, but here Bosola eighty-sixes the entire idea. If Fate exists (here characterized as the "stars") it's not some solemn guiding force that's deliberating over your existence, it's just deciding at random; The Powers That Be are basically playing ping-pong with your life. Bosola says this right after he accidentally kills Antonio, realizing that he lives in the same "general mist of error" (see Quote #5) as everybody else.
Quote #9
Pleasure of life, what is't? Only the good hours
Of an ague; merely a preparative to rest,
To endure vexation. (5.4. 67-69)
Check out some of Antonio's last words, uttered right after he's been stabbed by Bosola and then, finally, told that his wife and kids are dead. Despite everything that's happened, Antonio's been a pretty relentlessly glass-half-full kind of guy up until now. While he's previously voiced his belief that "Heaven hath a hand" in their sufferings (3.5.61), he's never, until now, embraced the Duchess's own wholesale-despair-of-life-itself outlook. Given that he just found out that his family, which he previously thought was safe, has been murdered, and that he himself is going to be joining them in about five seconds, we don't blame him.