What effect does Keating's teaching have on Knox?

In Dead Poets Society, the teacher Keating is all about Carpe Diem (seizing the day, or just going for it). He encourages his students to live life on their own terms, and question what they have been fed as the truth. With this in mind, Knox gathers the courage to pursue a the girlfriend of a football player (a football player is at the top of the social hierarchy in an American high school/prep school, and the fact that she was dating the athlete placed her out of Knox's league).