Throughout the first half of this chapter, Dorian is fraught with paranoia and fear that Victor will discover the secret of the portrait. Continuing the theme that was established in the preceding chapter, Dorian isn't enjoying the life he has chosen — even though he craves it more than anything. Instead of a life of glorious exploration and passion, he spends his time scheming and worrying.
Dorian seals his commitment to a life of vanity and debauchery when he hides and locks the portrait in the attic schoolroom. He rationalizes that he might, in fact, become more virtuous and reverse the moral decay reflected in the picture, but even he seems to know that will never happen. He seems to be thoroughly infected with the cynicism that Lord Henry has shown throughout the book; Dorian has been a good student of his mentor. It is enough for Dorian that he would wither and age without the portrait. He cannot and will not destroy the picture or attempt to negate the Faustian contract, if only because of his obsession with youthful beauty.
The first ten chapters of the novel cover a time span of about a month after Dorian and Lord Henry meet. In that time, Lord Henry's influence increases, and Dorian changes significantly. As Basil points out, Dorian is not the innocent, well-meaning young man who first posed for him. With Lord Henry's encouragement, Dorian has become self-absorbed and cruel. At first, Dorian may not have been aware of the seriousness of his wish to remain youthful while the portrait aged. By the time that he hides the portrait in the attic, however, he has every reason to know the consequences. He knows that the pact will "breed horrors and yet will never die."
