How we cite our quotes: (Act.Scene.Line)
Quote #7
There are a many ways that conduct to seeming
Honour, and some of them very dirty ones. (5.2.298-99)
The Cardinal has just asked Bosola to murder Antonio, promising that there are "honours" in store for Bosola if he goes through with it. There are, of course, multiple meanings for "honor" at work here. You have the moral concept of honor—conducting yourself in an honorable manner—and then there's what the Cardinal is implicitly offering Bosola, which is social distinction and reward. Bosola here is remarking upon the irony that, if you want the kind of honor that matters in courtly society, you have to do some pretty dishonorable things.
Quote #8
O penitence, let me truly taste thy cup,
That throws men down, only to raise them up. (5.2.339-40)
Raised up sounds pretty good, right? Bosola, having just decided to avenge the Duchess, sure thinks so. Having been bitterly disillusioned about his relationship with Ferdinand, Bosola now seeks the rewards of righteous revenge, thinking that he can depend upon Penitence (rather than a corrupt nobleman) to pay him back for his good work. And, well, we know how this turn out. The Duchess of Malfi: Where Good Guys Don't Just Finish Last, They Finish Dead.
Quote #9
How tedious is a guilty conscience! (5.5.4)
These are definitely not the words that you were expecting from the Cardinal. He's pacing around his palace, presumably thinking about the freshly murdered Julia and his slightly-less-than-freshly murdered sister. Do you think he's sincere? If you were the actor playing the Cardinal, would you make this sound sarcastic, or would you want it to sound as if the Cardinal is actually troubled by what he's done?