Silas is a bit naive in the beginning of the story. The writer's description of Silas is meant to lead toward a larger reveal when he is treated unjustly at the hands of many people. If the author had not chosen to build up Silas' character in the way that he did, then the unjust acts would not have had the emotional impact that they did. A very useful device in building up Silas' character is to contrast him with someone that is his 'foil' or his opposite. Despite the fact that William Dane is supposedly his best friend, it becomes evident to the reader, if not Silas, that he is not his best friend. Thus, when the betrayal happens, the reader feels it as acutely as does Silas. Silas' tragic flaw is exposed in the way he views the world the people he is surrounded by.