How we cite our quotes: (Scene, Line numbers)
Quote #1
MOTHER COURAGE: […] to Kattrin: 'Tain't your fault, you can't speak, I know. (I, 335)
Let's face it: when we talk about innocence as a theme in Mother Courage, we're usually talking about Kattrin. She is the one character who attempts to reclaim her voice, taken away from the war, by sacrificing herself to save others. This line is the first suggestion that Kattrin's inability to speak stands for her innocence and blamelessness. Though it seems insignificant, this line is important for allowing us to understand Kattrin's character development.
Quote #2
MOTHER COURAGE: Let that be a lesson, Kattrin. Don't you start anything with them soldiers. Love makes the world go round, I'm warning you […] Be thankful you're dumb, then you can't contradict yourself and won't be wanting to bite your tongue off for speaking the truth; it's a godsend, being dumb is. (III, 118-126)
This one seems a little counterintuitive, but Kattrin's muteness is often characterized as a good thing. For one, it means she's usually free of blame when things go wrong. But her mother also sees her muteness as a blessing because, as in this passage, it means she'll never be able to say she loves someone, or contradict herself, or speak the truth. All those things are framed here as ways innocence can be lost.
Quote #3
MOTHER COURAGE: […] Thank the Lord they're corruptible. After all, they ain't wolves, just humans out for money. Corruption in humans is same as compassion in God. Corruption's our only hope. Long as we have it there'll be lenient sentences and even an innocent man'll have a chance of being let off. (III, 644-649)
In Mother Courage's world, traditional values get turned upside-down. So, she can be grateful for corruption, since she's definitely not naïve enough to think that there will be justice for the innocent.