An introverted 19-year-old Leonardo leaves his parents' home and starts his adulthood. We're traveling with him a bit to London, but mostly to Siena, Italy, where he decides to study literature and, even more importantly, his independent life helps him discover his own personality, his tastes and fantasies. The film looks bold and shows things about the character that would normally be covert and even disgusting to see, but it helps us get a glimpse of the world he's starting to live in. If I didn't misunderstand, there's also a conflict between Leonardo's love for the literature, morality, restraint and norms of the 19th century (the title explains that) and his secret fantasies as well as binge-drinking that leads to him hospitalized by an ambulance, etc.
Personally, I didn't feel I could relate to this character but what I do relate to is the necessity of independence and self-discovery at this age that would pave the way for self-acceptance and a harmonious life as an adult. I'm not sure the film raised that but still, it was an interesting way of showing how this a bit weird teenager is becoming a weird adult.