"Clark Kent is the moral center that makes Superman. Clark is not simply a disguise behind which Superman hides. This is the truly unique and the single most important truth concerning the character. David Carradine in KILL BILL VOL. 2 got it wrong. The Superman/Clark Kent dynamic is not some clever reversal of the superhero template that spawned a genre in which the hero employs a disguise to fight evil, but is revealed by his civilian identity. In Superman's case, BOTH identities are the true identity. They are two halves of a whole. No other superhero can claim this reality.
But, again, the deeper truth is that Clark Kent MAKES Superman super. That is to say, Clark was raised by the Kents in Smallville with all of the critical traits needed to make and keep Superman moral, humble, altruistic, fair, brave, honest, virtuous, meek, and compassionate. The Kents provide Kal-El with his Earthly heritage, the heritage chiefly responsible for the most important element of Superman, his heart. So, Clark Kent is every bit as valid as Superman, and equally important to the overall character."
— Jerome K. Moore