Man, everything Mark is saying about Superman is right on point here.
For me, the Clark/Superman dynamic is one of the most interesting things in comics. They way I see it, there was a Clark - the boy raised on the farm, before his powers began to kick in. But that Clark would have withered, died, evolved as soon as he began hearing bacteria whisper conspiratorially, seeing the ebb and flow of energies cascading all across the biosphere, all the tiny joys and sorrows and hopes and fears of the human raise his bedtime story each night.
It's akin to Siddhartha's becoming the Buddha, to me.
So then what is Clark, as we see it now? I ask you this; in the aspiration of art, men create paintings, create music, create literature. But what would a SUPERman create?
A Superman would create...a man.
Clark is Superman's greatest achievement, his definitive statement on the human race. Clark is a work of art; a fully realized human being with his own foibles and insecurities and desires and strengths.
That, to me, is Clark.