...

«People have scars. In all sorts of unexpected places. Like secret road maps of their personal histories. Diagrams of all their old wounds. Most of our wounds heal, leaving nothing behind but a scar. But some of them don't. Some wounds we carry with us everywhere and though the cut's long gone, the pain still lingers. What's worse, new wounds which are so horribly painful or old wounds that should've healed years ago and never did? Maybe our old wounds teach us something. They remind us where we've been and what we've overcome. They teach us lessons about what to avoid in the future. That's what we like to think. But that's not the way it is, is it? Some things we just have to learn over and over and over again.» 

Meredith Grey (Ellen Pompeo) 

in "Grey’s Anatomy" (S3 E1)