There is a part in the song where the tempo is fast and the singing is full of emotions through the high notes. The singers are relay meaningful words and emotions in the songs.
This is comparable to one of my favorite songs in the recent years- Iris by Goo Goo Dolls. Similar to Erlknig of Franz Schubert, Iris also conveys meaningful story and full emotions. It is like an expression of a person's sentiments towards the society. It appears as a dedication to a certain person, filled with love and perseverance despite the apparent battle from the outside. I particularly liked the freedom of expression of one's self in the song.
The Romanticism period rejects the usual calm music found in the Classical period, that's why Romantic music are sometimes called irrational, but filled with expression and freedom. These are also the characteristics of the song Iris by Goo Goo Dolls. It is simply filled with freedom.