One of the realist elements of Madame Bovary is the logic of its plot, as it consistently foreshadows future events by introducing the catalyst of these events earlier in the novel. One example is the arsenic that Emma uses to commit suicide, which is introduced in Part 3, Chapter 2, where Homais yells at Justin while Emma is visiting:
– In a minute! Do you realize the risk you were taking?… Didn’t you notice anything, on the left, on the third shelf? Speak up, reply, produce some sound!
– I d-d-don’t know, stammered the young boy.
– Oh, you don’t know! Well I do know! You saw a bottle, a blue one, sealed up with yellow wax, containing a white powder, one with Danger on it in my writing, do you know what was in it? Arsenic!...You could have poisoned every one of us!
The novel lays out the details that will become crucial to Emma’s eventual suicide: what arsenic is, where the arsenic is, what the arsenic looks like, and who has access to the arsenic. The novel’s realism has conditioned the reader to realize that the plot predicates itself on a logical sequence of events, so Emma’s newfound thorough knowledge about Homais’s arsenic is expected to influence future events. This literary principle was later coined by realist writer Anton Chekhov as “Chekhov’s gun,” which suggests that if a gun is introduced in the first act, then it must go off by the end of the play. The arsenic’s foreshadowed use builds mystery and suspense, as the audience is aware that Emma will likely use it but is unsure of how until she asks Justin for the key to the Capharnaum a few chapters later.