Time is an idea fashioned by man to serve his purposes; the universe knows and cares nothing for our view of time and the importance we place upon it. Despite ones hopes, dreams or even the very action one takes in life; there is one inexorable factor that cannot be altered, the steady march of time and our need to move with it or risk being pulled down by our own inflexibility. In The Great Gatsby, the character of Jay Gatsby ignores this fundamental rule of human existence, choosing to live in a world of the past, created by his own memories, and avoid the changes of the present even as they cause his own demise. This character, through his thoughts and actions proves that the old axiom is true; you cannot go home again.
Jay Gatsby, despite all his successes and the seemingly plentiful life he led, is caught up in his own past and unable to break free from his own dreams of a lost innocence and his vision of recreating it in the now. Upon loosing Daisy after the war, Gatsby decided that his future must lay in his past; as there was no way that the exhilaration he felt with Daisy could ever be replaced, and so he created an elaborate plan to not only recreate his past but mould it in the context and direction he wished. Creating an empire for himself, a name, and status in order to be in the position now that he wished to have been those many years ago; ready to take Daisy in marriage and provide for her every need.
However, as time continues to move forward the reality of Gatsby's present situation begins to creep slowly into his fantasy world. One illusion to this comes from Gatsby's notice of the light on the end of Daisy's dock; it suddenly made the distance between himself and the woman he loved very tangible; and the hopelessness of his situation becomes represented by the large body of water that separates them. Whereas before he had noticed this light, the pursuit of Daisy and the reclamation of her love was a more of an ideal, and so Gatsby was free to mould it and romanticize this ideal as much as he wished.