Broken thumb of a statue
Lord Glenthorn falls so deeply into depression that he starts thinking of taking his own life, but every time he does come to that point there is something that comes along to save him. Such is the case of the broken thumb. In one of his lavish buying fits, he bought an extremely expensive statue, and while the statue was being unpacked, its thumb broke off. This ridiculous scene saved him because it turned his ennui into anger, and paradoxically he was happy to have something to complain about. So, following along with the dark humor of our protagonist, the broken thumb symbolically became a life-saver.
Pretty birds in a cage
The scene where a little girl is talking about Lady Geraldine and her companion as pretty birds singing in a cage is a rather striking one as it clearly represents the state of women of that time. Women were expected to find a good husband, look pretty and stay in the house, just like pretty birds. Lady Geraldine answers to the little girl that some birds can't live in a cage which speaks of her independent and self-aware character. This sort of allegorical use is rather simple and easy to spot, but nevertheless, its effect is still impactful.
Sage allegory
In his conversation to Mr. Deverux (who will end up marrying Lady Geraldine) Lord Glenthorn learns a rather important lesson from this wise man. He tells him of the story he heard from a philosophical friend about a strange plant growing in a mine. The plant turned out to be nothing but a common sage, but kept in dark it was so changed and degenerated that it looked nothing like itself. It is an allegory that implies Glenthorn's life, how he was kept in an environment where he couldn't be himself and at the end when he leaves that environment and is able to make his own choices is when he is truly content with himself.
