Castiel: At the time of the Great Fall, when the angels were banished from Heaven, I lost what I thought was everything. I had no grace, I had no... wings. I felt hopeless and useless.

Jack: What did you have left?

Castiel: Well... Well, I had Sam and Dean. But I had something else that was extremely helpful. I had myself. Just the basic me, as... as Dean would say, without all the bells and whistles. You know... Sam and Dean, they weren't born with their expertise. They've been at it since they were children. Failing, winning, developing over the years. Patience... persistence... Those are skills, too. The past, where you came from, that's important, but it is not as important as the future and where you're going.