Flashback

The narration interrupts the order of time and goes back to events prior to the point the story has reached.

In Madame Bovary

she wanted to get some personal profit from things [...] being of a temperament more sentimental than artistic, in search of emotions, not landscapes

The chapter leaves Tostes and goes back to Emma's years at the convent, before the marriage, which chapters 3 and 4 narrate. In this passage the narrator uses that past to explain where her way of wanting comes from: she "wanted to get some personal profit from things" and sought "emotions, not landscapes."

Part I, Chapter 6, the narrator

this spirit, practical amid its enthusiasms [...] who had loved the church for its flowers, music for the lyrics of its songs, and literature for its passionate excitement, rebelled against the mysteries of faith

Part I, Chapter 6, the narrator