His unreal and selfish love would yield to some higher influence, would be transformed into some nobler passion, and the portrait that Basil Hallward had painted of him would be a guide to him through life, would be to him what holiness is to some, and conscience to others, and the fear of God to us all. There were opiates for remorse, drugs that could lull the moral sense to sleep. But here was a visible symbol of the degradation of sin. Here was an ever-present sign of the ruin men brought upon their souls.

– Oscar Wilde

The Picture of Dorian Gray, Chapter 8. Dorian reflects on his "unreal and selfish love" for Sibyl and hopes that it will be transformed into something nobler. He would do this with the help of the portrait, a visible symbol of his corruption, which would be his conscience and he would use to guide him through life. As the battle for his soul between good and evil continues, he appears to find his moral compass and vows to follow the noble path. He does not yet know about Sibyl’s suicide.