What is the fine-grained topic of the following text: That Callow (last seen assuring a dim American dowager that he has Oscar Wilde’s fax number) is the author is not so odd: a long-time devotee of theatre and opera, he uses his theatrical sensibilities and wide research to unlock the artistic and egotistic impulses of the Maestro, all to good purpose. Only return the topic.
The author's use of theatrical sensibilities and research to understand the Maestro's artistic and egotistic impulses.