How we cite our quotes: (Volume.Chapter.Paragraph.)
Quote #1
"Never ask people. Not about your work. Don't you know what you want? How can you stand it, not to know?" (1.2.6)
Roark and Keating's early discussion about making decisions really sets up the contrast between the two men. Roark has always been certain and finds it upsetting to not know things.
Quote #2
"Do you always have to have a purpose? Do you always have to be so damn serious? Can't you ever do things without reason, just like everybody else?" (1.7.56)
Roark is logical, with a constant purpose, and Keating is more emotional and has trouble deciding. The two men's differences aren't used for comedic effect, sadly. Instead, Keating is just wrong and miserable and Roark is too cool for school.
Quote #3
He went away, relieved and desolate, cursing himself for the dull, persistent feeling that told him he had missed a chance which would never return [....] (1.12.269)
Keating is scared to make decisions and choices, and it's this character trait that drives his decisions (if you can call his actions "decisions" at all) and actions throughout the whole book.