What is the fine-grained topic of the following text: The crowd awaited in anticipation as Yusuf introduced the classic, “Father and Son.” Featured on the 1970 album Tea for the Tillerman, he told how the song was actually written for a never-produced musical project (“Revolussia”) about the 1917 Russian Revolution. Only return the topic.
"Yusuf's introduction and background of his song “Father and Son” from the 1970 album Tea for the Tillerman."