To me, it has to be when Roth delivers his "This is the business we've chosen" speech. To me, that is the most significant scene in all THREE movies.

There is so much going on here. On the surface, of course, it's just a WONDERFUL bit of dialogue. But underneath? You could interpret it SO many ways. Roth is obviously telling Michael he knows darn well who set up the hit on Moe Green. But I've always wondered whether this went deeper ... whether it was Roth's way to telling Michael (without telling him, of course) that he hadn't forgotten and that his time would come. Sort of like the "revenge is a dish that is best served cold" line in the book.

Thoughts, anyone?