Yup. Money.

Good point. Did you think that the blindfolded bank manager, stumbling away from the villains at the lake, was symbolic of Eddie's plight too?
Marlon, Claudia and Dimby the cats 1989-2005, 2007 and 2010.

The symbolism with the nuns-knuckles / government-jail sentence wasn't so much about him "getting clever", it was about him knowing his place. He wasn't really trying to be clever, he was trying to reduce his time so he could be there for his family. What the nun saw as a weakness in his "character" (talking back to an authority figure) she punished with a worse ruler smack. What Foley saw as a weakness (Eddie's need to reduce his time and what he was willing to do to reduce it) he exploited by demanding more information. In both cases "talking" (or the appearance of talking) resulted in "punishment". If he'd have known his place as a student he would have avoided a rap in the mouth. If he'd have known his place as a low-level criminal (and one with illusions of honor among thieves), he would have realized his attempts at sentence-reduction were hopelessunless he was willing to trade his life for less time. He was the smallest of fish.
"The things I do for love" Jaime Lannister

That is a great observation. I was kind of marveling at the makeup job on "Coyle's knuckles" (I doubt Mitchum sat in a chair for hours to make his hand look that way for the closeup) But, clearly another layer to it. Thanks for exposing me to this.
One more thing: I just watched Mitchum in 'Night of the Hunter.' He plays a phoney preacher with 'LOVE' and 'HATE' tattooed on his knuckles. So, I think it is fair to say that between Coyle and Night, Mitchum's acting tools include "method knuckle.":-)

My only complaint with the film is the outdated 70s funk soundtrack that diluted some suspense.
Are you for real? The music isn't outdated, it was highly contemporary. You couldn't get more 1973 than this even in 1973. What did you expect? Beethoven? Simon & Garfunkel? An 80's synth soundtrack like Miami Vice? The score was highly time appropriate, it's a 70's crime flick. This film without it's soundtrack would be like watching "Shaft" without Isaac Hayes

This message has been deleted.

Agreed.
I actually don't mind the soundtrack, the movie was released in 1973 so it's fitting. The green Road Runner and funky part of the score were used to alert the viewer that Steven Keats character was making an appearance.

Yep, good catch.
Excellent film. Just saw for the first time tonight after reading the book many years ago. My only complaint with the film is the outdated 70s funk soundtrack that diluted some suspense. But you can see the influence on Elmore Leonard and Tarantino with regard to wiseguy-speak.
A surprisingly good Boston accent from Mitchum.
Oddly enough, Government Center (where Peter Boyle exits the train station early in the film) looks today EXACTLY as it did when they filmed this in the early 70s.