The Divided Self

Just came across an unusual and thought-provoking line from Peter Watson's The German Genius:

More than one rider fainted from the heat but not the Kaiser's twelve year-old grandson, Wilhelm, who, despite his withered left arm, contemptuously refused to acknowledge a spectator who called out to him as 'Wilhelmkin'.

Naturally I initially struggled with the meaning of this, but now I take it to mean that the young Wilhelm's withered left arm did indeed wish to acknowledge the spectator's salutation but the rest of him refused to budge. His withered left arm must have had a sense of empathy the rest of his more robust self sorely lacked.