In The Sun Also Rises, Brett, Bill and Jake have an agreed upon system through which they express their struggle for meaning and value in life. In the novel, their system creates some challenge for Cohn who can't adapt his own system of meaning and value to accommodate theirs. Brett, Bill and Jake all share a system, or code, of meaning and value, based broadly on the exchange of something for another thing. In Brett's version of their code, utility is the overriding consideration: her struggle for meaning and value is attained when she utilizes "the full worth of her money" (eNotes). However, in her version of the code, true meaning and value are elusive because truly well utilized money is elusive.
Bill's version of the code emphasizes value of exchange. For Bill, meaning and value are attached to simple, daily exchanges of value: "You give them money. They give you" something of an equivalent value (eNotes). It is this exchange of value that purchases meaningful moments and provides the value of stature. Of course meaning and value are contingent upon recognizing and attaining equivalent values of exchange.
Jake's version of the code is a metaphysical capitalism, a system whereby he paid his "way into things that [he] liked" (eNotes). He acknowledge four means of payment for the privilege of being "into things" that he liked. He could pay by "learning"; by "experience"; by "taking chances"; or by "money." Jake's struggle for meaning and value was expressed in getting his "money's worth" and in "knowing when [he] had it." The drawback to this system of attaining meaning and value is that since it was possible to pay with your very life, you had to assess what you "liked" and the cost of payment very carefully.
Cohn, on the other hand, expects attaches his struggle for meaning and value in life to a romanticized perspective (eNotes): his meaning and value come from attaining internal goals derived from internal motivators. His internal goal is fame through literary accomplishment and specific physical luxuries. As a result, when Cohn and Brett and Bill and Jake get together, there is an unsuitable clash of values because Cohn's internal struggle for meaning and value can't be modified to accord with their external system expressing their struggle for meaning and value, while theirs similarly can't be modified to accord with his internal system.