Puttin' it in perspective...

The following is something I came across during some down time in Seattle...

"How long does it take to see the entire world Pa?"

"Well, that all depends upon who's seeing it. For me it would take just a blink of an eye because my whole world is right here."

"I can't imagine a man as sensible as Mr. Johnson allowing Johnny trapsing off to Mankato!"

Can you guess where this dialogue came from? If so, who is quoted in each line (all three lines are said by different people)?