In Van Houten´s letter to Gus, we find the title of hte novel. What does Van Houten mean by: "The fault, dear Brutus, is not in our stars/ Bun in ourselves"?

This is an allusion to Shakespeare's Julius Caesar. Cassius tells Brutus, "The fault, dear Brutus is not in our stars, / But in ourselves, that we are underlings." Cassius argues that we are the inventors of our own demise. John Green, however, uses this title as irony. Green implies that we are not the architects of our demise but rather part of the universe unfolding. Hazel and Augustus are merely a part of the constant chaos of the universe that affects us all. At least they can enjoy the moment.