"Everyone suspects himself of at least one of the cardinal virtues, and this is mine: I am one of the few honest people that I have ever known" (Chapter 3). The novel The Great Gatsby was written by F. Scott Fitzgerald. Nick Carraway has a special place in this novel, and it's not only because he is the narrator. He is not just one character among several, it is through his eyes and ears that we form our understanding of the other characters. If we were unable to have faith in his judgment, then our views of the rest of the characters would be unstable and doubtful. Nick goes to some length to establish his credibility, indeed his moral integrity, in telling the story about a "great" man named Gatsby. By gaining our trust of his morality throughout the novel, Nick has shown a clear and unbiased understanding of the characters.
Trying to gain our trust in his judgment, he starts off with a reflection on his own upbringing, quoting his father's words about how he has "advantages", which most likely are his spiritual and/or moral advantages. It seems as if Nick wants to show that his upbringing gives him the moral fiber with which to withstand and pass judgment on the amoral world of the wealthy, such as the people and society he had observed the in summer in New York. He says, that as a consequence of such an upbringing, he is "inclined to reserve all judgments" about other people, but then goes on to say that such "tolerance . . . has a limit".
From this we first learn to trust Nick to give us an even-handed insight to the story, and its characters. But, he neither reserves all judgments nor does his tolerance reach its limit.