Steppenwolf The disease in Steppenwolf is a disease that, as stated in the book, “….affects not only the weak and the worthless but also the strongest in spirit and the richest in gifts.”. This disease is loneliness. Some would not call this a disease, they would call it a feeling. It, in fact, really is a disease affecting the thoughts, feelings, and actions of a person, and in this case Harry Haller, or the Steppenwolf. This disease, which affects the innermost parts of a person’s soul, has affected Mr. Haller for quite some time. Loneliness can change a person greatly and, if