Doctor Strong is the headmaster of the school David attends in Canterbury. He is an aging, scholarly man whose primary goal in life is to develop a new dictionary. Nevertheless, he is extremely considerate of those around him and is generous to a fault: for instance, he either does not notice or does not care that his mother-in-law, Mrs. Markleham, is using him to advance her relatives' prospects. Doctor Strong's kindness makes him a favorite with his students but actually places some strain on his marriage. In his selflessness, Doctor Strong assumes that if his wife, Annie, truly is having an affair with her cousin, Jack Maldon, it is the Doctor's own fault for marrying a woman so much younger than himself. This leads him to push Annie away, much to her distress, and the misunderstanding is ultimately resolved only through Mr. Dick's intervention.