When you're a young man, Macbeth is a character part. When you're older, it's a straight part.

The young man who has not wept is a savage, and the older man who will not laugh is a fool.

Go West, young man.

Go west, young man.

A young man is a theory, an old man is a fact.

My dear boy, why don't you try acting? (on the set of 'Marathon Man', to Dustin Hoffman, who had announced that he'd gone 3 days without sleep in order to 'become' his character