All these fortuities combined to give Tereza the courage to go to Prague to see Tomas.
We are daily bombarded with coincidences, explains the narrator, and we don't notice most of them. But for Tereza, love "inflamed her sense of beauty," making everything around her take on a sense of beauty.
In the book, Anna Karenina, which Tereza carried with her to Prague, Anna and Vronsky meet in a train station, where someone is run over by a train. At the end of the novel, Anna throws herself under a train. This is a very symmetrical composition, says the narrator, and it probably seems very "novelistic" to you.
The narrator is willing to agree that it is very literary, but warns you against calling it contrived or fabricated. "Human lives," he argues, "are composed in precisely such a fashion" (2.11.3).
In fact, human lives are composed like music.
A given motif takes up a permanent place in a person's life (Beethoven is Tereza's motif) and without knowing it, "the individual composes his life according to the laws of beauty" (2.11.4).
Therefore we shouldn't criticize novels for being contrived when such coincidences occur; we can only criticize man for being blind to such coincidences in real life.
When you ignores these kinds of coincidences, you deprive your life of beauty.