Mary shelley husband was famous for his romantic poems and qoutes, he tried to invite mary into the " free world has he called it. I believe that his free sprited way help endorse mary shelly novels. Percy has a qoute that I feel stands out greatly in Mary book novel " Frankestein" ( Fear not for the future, weep not for the past). I think she used that qoute in the book when Dr Frankenstein tried to argue his point that science is need of chnage. (source) aztec.com