In The Picture of Dorian Gray, youth is illustrated as a delicate state which leaves us at any moment, and its loss is a symbol of disgrace. This is why Dorian became adamant that he would not want to age, and wished that the picture would. It is also illustrated as an omen of disaster. It is disturbing in the story how characters who had aged in more than 20 years suddenly find Dorian walking around and not having aged. That is an element of terror, and what makes the story scary.
Mortality is illustrated in the death of Basil and his posterior cremation by Dorian's indebted friend. It is disregarded as a romantic process. When Sybil Vane killed herself, Harry said he was glad to live in a time and place where things so intense are able to happen. Dorian dismissed it as a rebirth for himself, and used it as a symbol of sacrifice (which he would never do).
Good vs. Evil is illustrated in Basil and Harry. Basil shows a true and honest love for Dorian, and he protects and cares for him. Harry has the evil side which tempts and lures Dorian into sin.
Art is seen as a revealer of the artist, but then as a concealer of the artist. When Basil laid "all of himself" onto the picture, he feared that he had said "too much" about his admiration for Dorian. Yet, as the suppressed paragraph of Dorian Gray that was read at the Old Bailey during Wilde's trials, he ended up admitting that "form and color is just form and color" and that art helps the artist actually protect himself from the world outside.
Culture is entirely left to the upper classes. The theatre is for the rich, but acting is for the poor. The so-called "Idle Classes" are the epitome of a life through contemplation, and not laziness. Philanthropy is seen as an unnecessary waste of intellect. All these are cultural factors inherent to the rich, and are all represented by Harry himself