“It’s not who we are underneath, but what we do that defines us.” -Rachel Dawes in Batman Begins
What may be the most profound quote of Batman Begins is uttered by Rachel as a slap in the face to Bruce Wayne. Later on though, Batman uses it as his way of revealing to Rachel his true identity.
It’s a beautiful quote, seeping with wisdom and truth. It really is what we do that defines us, regardless of whether or not that matches what is underneath. That realization plays well into the developing theme of Batman as not just a person, but as a symbol; how any number of people could be Batman, it just happens to be Bruce Wayne within the suit.
It also speaks so directly to the dual-identity life that all superheroes are faced with, and the struggle of whether or not to share their secret with those they love. Even though who we are underneath doesn’t directly define us, the internal conflict he faces directly inspires Batman’s actions, which are seen by all.