What is the significance of the book's epigram by Juan Ramon Jimenez: "if they give you ruled paper, write the other way."?

Fahrenheit 451 is all about rebellion. Montag is not born again until he rebels against the status quo. Meaning in life does not begin until he actively rebels against the burning of books. The above quote incites rebellion. Writing the other way is an act against what is accepted by greater society. It is a metaphor for challenging and changing what is generally accepted.