Close read of the conversation between Sydney Carton and the wood-sawyer in Chapter IX The Game Made A Tale of Two Cities

This conversation stands out to me because it is a demonstration of the two perspectives on the use of the Guillotine.  Sydney Carton is absolutely appalled, not only at the simple fact that the Guillotine is employed, but that normal, everyday people are finding such amusement and enjoyment at the display of the Guillotines use.  The sawyer is one of the many that is greatly amused by the spectacle of the beheadings.
The guillotine itself allows for the executioner to perform his brutal task without doing the dirty work of the beheading himself.  He simply must throw a switch and effectively ends the life of one of the condemned, automatically and without emotion.  The process has become so automatic and thoughtless that the sawyer likens the executioner to a "barber" and the action of the guillotine administering a beheading as "shaving". 
It's almost as if Dickens is clashing good and evil.  Carton represents the human desire to be just and peaceful while the sawyer represents the "mob mentality" or kind of "go-with-the-flow" mindset that grips people in times of desperation; bad things happening to someone else make the bad things in our own lives seem more bearable.
Dickens, in this short section of only a few paragraphs, points out both the good and evil that is in all of us.