What paradox of life did the narrator talk about? How did he illustrate his view?

J. uses this as an occasion to meditate on how people always want what they cannot have, and do not want the things they do have. He recalls a former classmate named Stivvings, who was dedicated to his studies but was often too sick to complete his work. Meanwhile, the other boys hoped to get sick to avoid schoolwork, and became sick only when vacation came around.