One of the most compelling of those factors has been social relevance. Dylan benefited from that as much as anyone, breaking into the music world as a "protest" singer in the folk scene of New York City in the 1960s, even though he soon bristled at that label.
That kind of interest in popular music as an expression of counterculture attitudes or protests about social injustice make rap interesting to some scholars.
"I think you're going to find that through the growing power and growing strength of people interested in the African-American culture, you're going to find some rap MC's looked at seriously," Shusterman said.
Though Shusterman, when challenged by fellow scholars to turn his attention to something more mainstream, wrote a book on country music, said he believed "it will probably take longer" for a country singer to get the kind of close, serious reading that Ricks has given Dylan.
"Academia sees itself as a kind of counterculture world," he said. "Country singers are seen as more mainstream."
But Ricks didn't talk about any of that when he was asked why he wrote this book, making room for Dylan alongside Eliot and Shakespeare.
"I resist the idea that I have some kind of monomania," he said. "But I've listened to him for 35 years and nobody else comes home with the same poignancy."