The repetition of "habit" in relation to Dr. Monygham's jacket calls
attention to the pun: "habit" can mean both behavior and clothing. The
narrator thus subtly denigrates Dr. Monygham's cynicism to something put on, an
artifice deliberately chosen, albeit at a deep level of personality. See also
the statement that Monygham "had made himself an ideal conception of his
disgrace."
Similar comments will be made about other characters' dream-ideals, suggesting
that at some level we all choose the ambitions or ideals that later come to master
us.