For there would be a real pleasure in watching it. He would be able to follow his mind into its secret places. This portrait would be to him the most magical of mirrors. As it had revealed to him his own body, so it would reveal to him his own soul. And when winter came upon it, he would still be standing where spring trembles on the verge of summer. When the blood crept from its face, and left behind a pallid mask of chalk with leaden eyes, he would keep the glamour of boyhood. Not one blossom of his loveliness would ever fade. Not one pulse of his life would ever weaken.
– Oscar Wilde
The Picture of Dorian Gray, Chapter 8. Dorian is now comfortable with the fact that he will be eternally young, despite having traded his soul for it. So he will take pleasure in watching the changing portrait, a magical mirror that will show him his own soul. When the face in the picture crumbles into a bloodless mask of chalk with leaden eyes, he will enjoy the beauty of youth. His portrait has turned into something supernatural, a picture of his changing soul. At this stage Dorian is the complete narcissist.