what theme is fitzgereald is bringing to light via nicks musings of kant

Immanuel Kant, a German philosopher, said that he developed his theories regarding reality and morality while gazing at a church steeple outside his window. Similarly, Nick ponders life while staring at Gatsby's house. For much of the novel, Gatsby is an enigma bordering on the spiritual for Nick. At this point in the novel Nick sees only the mystery of how Gatsby seems to become larger than life.

"There was nothing to look at from under the tree except Gatsby’s enormous house, so I stared at it, like Kant at his church steeple, for half an hour."