Dan Cody was Gatsby’s best friend. Dan Cody played a very big part in Gatsby's life. Gatsby also has a picture of him hanging in his wall. Gatsby’s new life began on the lake when he met Dan Cody. Dan Cody was a wealthy copper minor from Montana. Gatsby and Cody both sailed around the world together three times over the next five years. During this time, Gatsby served as steward, mate, skipper, and secretary for Dan. Gatsby had to jail Cody on occasion to prevent him from committing dangerous acts.



Dan Cody was a somewhat coarse man who became very wealthy during the Gold Rush. The transactions in Montana copper made Cody a great millionaire. Cody was softminded, and naive, and many young women took advantage of this. He mentored Gatsby, when he was a young man and gave him a taste of elite society. He taught him how to do business, and he taught him all he knew.



Plus, he had an insatiable thirst for alcohol and drank continuously. Before Dan Cody died, he left Gatsby a large amount of money, because Gatsby had helped and taken care of him. Also, Dan Cody did influence Gatsby in many ways; most importantly, watching Cody's excessive drinking, made Gatsby drink very little. A portrait of Cody hangs on Gatsby's wall. Gatsby used this money to start the business that he is now in. And he uses what Dan Cody taught him to run his own business. (http://www.enotes.com/great-gatsby/q-and-a/chapter-6-great-gatsby-87159)