I doubt anyone remembers, but a while ago I was wondering about a certain Joan of Arcadia quotation and no thanks to you fine readers, I've finally found it. It's from the episode, "Drive, He Said," and it goes a little something like this:

Being an adult isn't merely about risking your own well-being. It means risking others'. In cars, in love, in family-- hurting others is always a possibility. That's what's difficult about being an adult, facing the harsh fact that you may hurt others, even when you don't want to.

(Gotten from this site.)