Epigraphs are like little appetizers to the great entrée of a story. They illuminate important aspects of the story, and they get us headed in the right direction.
"It is certain my Conviction gains infinitely, the moment another soul will believe in it." – Novalis
Novalis? Who? Nope, he's not some Greek philosopher or Roman poet. Novalis is the pen name of a German Romantic writer named Georg Friedrich Freiherr von Hardenberg. Yes, really.
It's fitting that Conrad would pick a guy like Novalis to quote for an epigraph. Lord Jim pays a lot of attention to the power of a romantic imagination and the influence of romance novels on Jim. Jim is described throughout the novel as a "romantic," and his romantic, unrealistic ideals land him in hot water time and time again. They cause him to behave erratically and to have trouble handling realities, like the disillusioning Patna incident.
Aside from this nod to romance, the epigraph has significance for what it's actually saying. Awesome. So what is it actually saying, then?
In this quote, Novalis suggests that it's more important to convince others to believe in you and your conviction than to have conviction in the first place. Your conviction doesn't matter much without the belief of others.
Lord Jim is all about belief. Storytellers like Marlow need their audience to believe that they are telling the truth, and sailors like Jim need others to believe that they are good, noble folks. It's all about how others see you in Lord Jim, and we can't help but wonder if Jim read a little more Novalis than was good for him.