He was prisoned in thought. Memory, like a horrible malady, was eating his soul away. From time to time he seemed to see the eyes of Basil Hallward looking at him. Yet he felt he could not stay. The presence of Adrian Singleton troubled him. He wanted to be where no one would know who he was. He wanted to escape from himself.
– Oscar Wilde
The Picture of Dorian Gray, Chapter 16. When Dorian arrives at the opium den, a vivid simile is used to describe how his memory is like a disease killing his soul. Riddled with guilt he is haunted by images of his murder victim Basil, who symbolized the goodness in humanity. He is also troubled by the presence of Adrian Singleton in the opium den, who has become an addict because of Dorian.