From the Professor:
Please imagine you’re Eveline’s confidential friend and it’s a day or two before the story opens. Concerned about her in her crisis, you write a letter to Eveline persuading her that she should or should not leave with Frank—for this assignment she has only two options. Your letter must present in detail the cases as you see them for her staying and for her leaving. Your argument (to stay or leave) should be made in the second half of your letter in what’s called climactic order, on the principle of saving the best for last.
Since you’re meaning to persuade her, in your letter you want to get across to Eveline that you’re intimately acquainted with her predicament, hence your presentation of both sides of the argument.
Meaning to prevail upon your friend, you give yourself the last word—you save your best, your argument (to stay or leave) for last.