What is the quote that the old man says is the reason for the blacksmith's departure?

he short answer is "Just because". Candy explains that Whitey used to use George's bunk and was paranoid about bugs. One day Whitey picked up his check and moved on. He gave some of the usual excuses but in the end he "just wanted to move on down the road." Whitey is an example of the transient life that these men live.