Diana Gabaldon said this quote

And I tell you what, L.J.; you see all these people you haven't seen for twenty years, and there's this split second when you meet somebody you used to know, and you think 'My God, he's changed!,'and then all of a sudden, he hasn't- it's just like the twenty years weren't there, I mean he rubbed his head vigorously, struggling for meaning--you see they've got some gray, and some lines, and maybe they aren't just the same as they were, but two minutes past that shock, and you don't see it anymore. They are just the same people they always were, and you have to make yourself stand back a ways to see that they aren't eighteen anymore