He takes an interest in horticulture, but after experimenting with silk flowers that ape real flowers, he experiments with real flowers that mimic silk flowers. He experiments with scents and perfumes, working up to inventing the perfume organ. Literature, music, food, sex, precious gems, etc. ... he tries them all, but seemingly finds satisfaction nowhere. Anomie, alienation, abnormality... it does get to be a bit much, but there are some splendid scenes.
But don't take my word for it; Dorian Gray has a similar reaction:
[Dorian's] eye fell on the yellow book that Lord Henry had sent him. What was it, he wondered. ... After a few minutes he became absorbed. It was the strangest book that he had ever read. It seemed to him that in exquisite raiment, and to the delicate sound of flutes, the sins of the world were passing in dumb show before him. Things that he had dimly dreamed of were suddenly made real to him. Things of which he had never dreamed were gradually revealed.
It was a novel without a plot and with only one character, being, indeed, simply a psychological study of a certain young Parisian who spent his life trying to realize in the nineteenth century all the passions and modes of thought that belonged to every century except his own, and to sum up, as it were, in himself the various moods through which the world-spirit had ever passed, loving for their mere artificiality those renunciations that men have unwisely called virtue, as much as those natural rebellions that wise men still call sin. The style in which it was written was that curious jewelled style, vivid and obscure at once, full of argot and of archaisms, of technical expressions and of elaborate paraphrases, that characterizes the work of some of the finest artists of the French school of Symbolistes. There were in it metaphors as monstrous as orchids and as subtle in colour. The life of the senses was described in the terms of mystical philosophy. One hardly knew at times whether one was reading the spiritual ecstasies of some mediaeval saint or the morbid confessions of a modern sinner. It was a poisonous book. The heavy odour of incense seemed to cling about its pages and to trouble the brain. The mere cadence of the sentences, the subtle monotony of their music, so full as it was of complex refrains and movements elaborately repeated, produced in the mind of the lad, as he passed from chapter to chapter, a form of reverie, a malady of dreaming, that made him unconscious of the falling day and creeping shadows.
[The next day]
"I am so sorry, Harry," he cried, "but really it is entirely your fault. That book you sent me so fascinated me that I forgot how the time was going."
"Yes, I thought you would like it," replied his host, rising from his chair.
"I didn't say I liked it, Harry. I said it fascinated me. There is a great difference."