Steppenwolf plans to play chess, but he is distracted by the gallery labeled "MARVELOUS TAMING OF THE STEPPENWOLF." He recognizes the animal tamer as himself, mean and absurd. The man commands the wolf to perform menial tricks such as kneeling, playing dead, carrying food in his mouth, and retrieving the whip. The wolf is forced to jump over a rabbit and a lamb, and then embrace them while eating chocolate. Steppenwolf is horrified to witness such annihilation of the wolf's nature.
The wolf and man switch roles. The wolf commands the man to drop to his knees and tear off his clothes. The man walks on two feet and all fours, plays dead, allows the wolf to ride his back, and retrieves the whip just as the wolf did previously. He frightens a young girl who shows him affection. Later, he rips the rabbit and lamb apart and devours them. Steppenwolf is shocked and disgusted and runs for the door. He leaves the gallery with "the taste of blood and chocolate in [his] mouth." He remembers pictures from the war and feels self-aversion.
The third gallery is even more disturbing than the war against the machines. Although Steppenwolf participated in the war with Gustav, it was not overtly about him. MARVELOUS TAMING OF THE STEPPENWOLF is about him and nothing else. He has always claimed that his soul is divided between man and wolf, and once he reads the treatise, Steppenwolf is convinced that it is true since it is documented as such by an outside source. Even so, he has never seen the division of himself and the subsequent tension it creates from an external perspective.
The fact that Steppenwolf is confronted with his "diabolically distorted double" first makes him sympathetic to the wolf. He is disturbed by the man's subversion of the wolf's nature. Forcing the wolf to perform tricks and denying him prey is unnatural and wrong. Similarly, suppressing the man's desire to walk on two legs, wear clothing, and converse with other humans is contrary to nature. Compelling him to rip apart raw flesh and consume it is barbaric.
At this point in the novel, Hesse is creating an image of Nietzsche's philosophy. Nietzsche supports nihilism, the idea that a divine being does not exist, nor does knowledge, nor any type of value system. According to Nietzsche, anything that denies or attempts to suppress desire is, by default, unnatural and wrong. Steppenwolf sees this firsthand in this gallery, and it is all the more horrifying because it personifies Steppenwolf's own nature. He has always believed the battle between man and wolf to be a violent struggle for domination, but up until this point, he has not realized that one part of his nature will always be forced into a state of perversion. The treatise acknowledges this: "the man and the wolf did not go the same way together, but were in continual and deadly enmity. One existed simply and solely to harm the other, and when there are two in one blood and in one soul who are at deadly enmity, then life fares ill."
diabolically wickedly, cruelly, fiendishly.
aping a person who imitates; mimic.
belie to give a false idea of; disguise or misrepresent.
dissimulation a state in which one hides by pretense.