In the passage, Isabel observes the doctor’s habit of drumming his fingers on the table, which hints at his impatience. She reflects on how such gestures often stem from prolonged discussions with patients who may not articulate their problems as clearly as he would prefer. This brings to mind that certain professionals, like doctors and lawyers, can develop a sense of superiority due to their constant interaction with people who struggle to express themselves effectively.

Isabel's inference about the doctor suggests a deeper exploration of the dynamics between professionals and their clients. She argues that spending too much time around individuals with more mundane or flawed perspectives can skew one's view of their own intellectual standing. It serves as a reminder of the importance of empathy and humility in any profession, as excess exposure to the limitations of others might lead to an inflated sense of self-importance if not checked.