Nostalgia: the pain from an old wound

This is probably  the most popular lines from the popular and critically acclaimed episode of Mad Men. It almost  brought me to tears. But probably  you wouldn't  get the whole meaning  or why those  words were so powerful without  a little background  on Don Draper's life. Anyway, here are the lines.

Draper: "Teddy told me that in Greek nostalgia literally means, the pain from an old wound. Its a twinge, in your heart. Far more powerful then memory alone. This device isn't a spaceship, its a time machine. It goes backwards, forwards. It takes us to a place, where we ache to go again. It's not called "The Wheel". Its called "The Carousel". It lets us travel in a way a child travels. Round and round, and then back home again. To a place where we know we are loved."
-- Don pitching "The Carousel" to Kodak, in The Wheel

Here's the youtube link to the video