That, they never could lay their heads upon their pillows; that, they never could tolerate the idea of their wives laying their heads upon their pillows; that, they never could endure the notion of their children laying their heads upon their pillows; in short, that there never more could be, for them or theirs, any laying of heads upon pillows at all, unless the prisoner's head was taken off.
I really like the balance Dickens is setting up here. It's a bit sarcastic and pokes fun of those who genuinely believe that life would be better, and they would be safe if this random man's head was brutally taken off and body severed. He's calling out a divide that exists between a jury (those who decide your fate) and what little control you have on life (while they could care less).
